Eurasia: the world's largest land mass.
Some 10,000 kilometers from the Pacific to the Atlantic ocean.
A formidable distance, even in today's world.
And yet over that vast distance,
human beings have pursued one of history's greatest enterprises:
The Silk Road.
A tremendously profitable trade route
and so much more.
For thousands of years,
exotic goods,
new technologies,
conquering armies,
and brilliant ideas
traveled along the Silk Road.
Silk Road trade helped to build empires
and to break them.
It fanned the fires of revolution.
Drove great explorations,
and forged powerful bonds between far away peoples.
The Silk Road made human beings realize
that there are other people out there,
and it opened the eyes of the east and the west.
This is the story of how Silk Road trade made so much more than money.
It's the epic tale of how the Silk Road helped create a world;
a world that created us.
2,000 years ago, the Roman Empire seemed unstoppable.
Rome had conquered much of Europe
and was sending its legions beyond the eastern Mediterranean
to the Middle East
-- gateway to the riches of Asia.
But a journey to the east could become a road of blood.
In 53 BC. near the Mesopotamian town of Carrhae,
the Parthians — an empire blending Persian and Greek cultures —
confronted a Roman army.
The outcome of the battle seemed beyond doubt.
Some 40,000 Romans faced only 10,000 Parthians.
And Rome's legions were Europe's finest foot soldiers.
There was just one problem.
The Parthian army didn't fight on foot.
The Parthians, they were cavalry.
They were horse archers.
Versatile. Rode like the wind.
What the Romans did was what the Romans always did.
They took a fixed position.
They were ordered into a hollow square defending all sides.
But that was nothing to the Parthian horse archers
because they could just ride around them, and they did.
They galloped around and around and around and around,
shooting as they went.
Thousands and thousands of arrows loosed into those Romans.
What the Romans eventually did was they were ordered to go into testudo.
That's that Roman formation where they lock their shields together
and put the next layer of shields to make a roof.
Testudo is Latin for tortoise.
But the Parthians had the answer to this tortoise.
They had a hammer to break open its shell.
The Parthian hammer was a cataphract,
a Greek word meaning "clothed in full armor".
Horse and rider wore heavy coats of mail.
The cataphract was the ancient world equivalent of a battle tank.
At Carrhae, charging cataphracts broke open the testudo.
Exposing the Romans inside to more arrow attacks.
Some 30,000 Romans were killed or captured.
Parthian losses were minor.
It was one of Rome's worst military defeats.
But it may have been something else as well.
A Roman historian wrote
that the Parthians dazzled the Romans
with banners made of a beautiful fabric:
silk.
That may only be a legend.
But around the time of Carrhae,
Romans began coveting Chinese silk,
and China began selling silk to Rome
in exchange for fine Roman glassware and gold.
Inspiring the name we give Eurasian trade today:
the Silk Road.
But long before Romans and Parthians fought at Carrhae,
trade between the peoples of Eurasia were shaping lives,
making new things possible,
and changing the world.
At Carrhae, the Parthians won with a style of warfare
that had evolved centuries earlier
and thousands of kilometers away.
On the steppes of Central Asia,
an ocean of land,
where victory in battle, and life itself,
depended on moving very far, very fast.
Thousands of years before the battle of Carrhae,
a transportation revolution took place on these vast plains.
There's good evidence for the existence of domesticated horses
in what is today Kazakhstan and southern Russia by 3500 BC.
And we actually think that probably horses were domesticated
and began to be ridden 500 or maybe 1,000 years before that,
maybe as early as 4500 BC.
The domestication of the horse
was the first step towards cavalry warfare.
But the second step would be a long time coming.
The first use of horses in warfare was with chariot warfare,
and we have that well established Tutankhamun's chariot,
which many people have seen in museum exhibits.
And we know that people were using chariots in warfare
starting in the Near East in about 1600, 1700 BC..
Horses were not used as organized cavalry
until after about 900 BC,
almost 1,000 years after chariot warfare began.
And it's always seemed odd to me that cavalry began after chariotry.
Chariotry is very difficult to manage.
You have to train horses to work together.
They have to pull this clumsy vehicle
that has two people in it: a driver and a warrior.
Training the units to work together, very difficult thing to do,
whereas jumping on the back of a horse is an easy thing.
So, why did cavalry come after chariotry?
I think the real reason that cavalry waited
is that you needed to have really three innovations.
The earliest evidence for the recurved bow is in Shang Dynasty, China,
probably dated between 1300 and 1100 BC.
Shang emperors communicated with their ancestors
by heating animal bones or turtle shells until they cracked
and then interpreting the patterns made by the cracks.
One of these so-called oracle bones
is carved with the Chinese character for bow
— the earliest known image of a recurved bow.
And in the tomb of Lady Fuhao
— an imperial consort and renowned military commander —
archaeologists found more evidence.
It's a thumb cover for drawing bow string
and there's another piece that went in the middle of a recurved bow,
a hand grip.
The bows themselves are not preserved,
so, it's a difficult thing to identify the origins of the recurved bow.
The different components of it
probably came from different places geographically.
Just how far the recurved bow traveled across Eurasia
was revealed in 2005 at Yanghai, in China's Xinjiang region.
Wooden bows rarely survive burial in the ground,
but Xinjiang's cold, dry climate preserved one
in a 3,000-year-old tomb.
Other grave goods and the human remains
found in the Yanghai tombs
confirmed that the bow was made by the Scythians,
a highly sophisticated culture that originated in southern Russia
and migrated on horseback
across the length and breadth of Eurasia.
The true birthplace of the recurved composite bow
remains an archaeological mystery.
But there is no doubt that 3,000 years ago
anyone who fought on horseback would have found it revolutionary.
A bow is as strong as it is long.
It derives its strength from its length.
And the recurved bow packs the same length
into this very short bow
that can be swung over the horse's rear and over the horse's neck.
And it was much, much easier to use on horseback.
And the recurved bows are technologically quite difficult to make.
It took a long time to develop the craft of bow making to that point.
The recurve all these sinewy bends — reflex and deflex —
that gives it in-built spring.
But that can only be created with composite materials.
What we mean by that is it's made of a number of materials.
The heart of it is wood, usually beech.
And then you have horn, horn from a water buffalo,
and then sinew, the tendons of an animal.
That, when you bash it,
you can tease apart and get these very fine fibers,
fibers with tremendous tensile strength.
That has elasticity and spring,
and it stops the bow bursting apart.
These are all materials that enhance the power, the spring of the bow.
But only if bow makers could solve a very big problem.
How to keep such a powerful bow
made from so many different materials
from breaking up when its own power was pulling it apart?
Somewhere in Eurasia, sometime long ago,
some unknown genius discovered the answer.
This is the swim bladder of a sturgeon — a fish from the Black Sea.
And if you start to break these up then put it in hot water,
and you get this wonderful, viscous glue.
This simple idea of making a glue out of a swim bladder of a fish
was a technological breakthrough of immense consequences.
It is what enabled the composite bow to exist.
And in turn the composite bow was a military revolution
of far-reaching consequences.
The composite recurved bow gave birth to a new kind of warrior
the horse archer.
The horse archer was able to shoot from the saddle
in part because of the new technology of the composite bow.
They were short, compact bows,
and that meant that you can shoot them from horseback.
You see I can cross to the other side of the horse,
I can turn and shoot behind.
It's much more suitable for shooting on horseback.
Everyone who fought with Eurasian nomads,
whether as enemy or friend,
wanted a recurved composite bow.
By the early first millennium BC,
it was in use from east Asia to eastern Europe.
A recurved bow gave a horse archer unprecedented killing power.
But it didn't make him a cavalryman.
Before horse archers could fight as an effective military force,
they needed a large supply of identical arrows.
And that didn't exist.
Arrowheads were a variety of different sizes and weights.
Some were made of bone.
Some were made out of flint.
Some were made out of bronze.
All of them would be individually made
and you had to adjust your shot for the weight of different arrows.
Also a unit of soldiers who were firing at the same time
would be firing arrows of slightly different weights
and they might go different distances.
One of the features of a stone arrowhead is its flattened rear
But how did it connect with the arrowshaft?
It can only be tied to the shaft by rope or ox tendons.
But what about the disadvantages?
First, the released arrows tend to change direction easily.
Second, they are likely to fall off,
One of the technological innovations
was the invention of the socketed arrowhead.
They were made of bronze, usually,
and they were made in a mould and cast in a mould,
so that an infinite number of socketed arrowheads of the same weight
could be made from the same mould.
Making socketed projectile points was actually a big deal.
You have to have a mould with a core where the socket is going to be
that you can pour molten metal around
so that it's the same thickness all the way around.
Making arrowheads of the same size and weight
was another Central Asian technological revolution.
For the first time, mounted warriors could unleash
coordinated arrow attacks on their enemies.
With arrowheads of the same weight,
every time you drew the bow to shoot
you knew that you were firing an arrow
that was exactly the same weight as the last arrow that you fired,
so you could determine the range and the distance well.
And also all of the archers that were firing
were firing arrowheads at the same weight at the same time.
So the distance for all of them would be the same.
With a socketed arrowhead
you can directly insert the head into the shaft.
It look like this.
So what are the advantages of this type of arrowhead?
Its improvements greatly enhanced
the lethality and efficiency of ancient arrows.
Even in the chaos of war, the shooter could aim t the target easily.
He wouldn't loose the direction by aiming t the target quickly.
This ivention is a giant leap in the development of human history.
Archaeologists believe that sometime in the second millennium BC,
socketed bronze arrowheads began spreading east
while the composite recurved bow spread west.
Sometime around 900 BC,
socketed arrowheads and recurved bows
met in the Tarim Basin area of Central Asia,
brought together by traders, warriors, and migrating nomads.
After about 700 BC, you begin to see thousands and thousands of arrowheads
and dozens of arrowheads in a single quiver in a grave.
It's like they're being mass produced.
Bronze socketed arrowheads turned central Asia into an arsenal,
but cavalries still couldn't exist
until warriors could become soldiers.
It was really the age of heroic warfare
— individuals going out and doing great deeds by themselves
and attracting glory for their own name.
And this is the kind of warfare that's described
in the "Iliad", in the "Odyssey," or in the "Rigveda,"
a religious text that's at the deep roots of modern Hinduism.
What had to change was a psychological change
in the nature of the warrior.
You had to change from individuals to units
working under the command of a commanding general,
who would attack and retreat upon command.
The psychological change from the heroic warrior to the soldier,
probably is a feature of urban warfare.
The armies that were associated
with the great cities of Mesopotamia and Iran.
That psychology had to spread northward up into the steppes
and be accepted by warriors in the steppes,
in the same area where the recurved bows
and the socketed arrowheads were crossing.
While recurved bows were spreading west
and socketed arrowheads were spreading east,
the concept of military discipline was spreading north.
Sometime around 900 BC,
all three combined in the heart of central Asia.
When those three things came together,
cavalry became a really deadly form of military force.
A force that would severely test the ancient world's most powerful armies.
2,000 years ago,
as the Romans pushed east to expand their empire,
China was pushing west.
And like the Romans,
the Chinese encountered a formidable enemy on horseback.
The Xiongnu were nomads from the Central Asian steppes.
Armed with recurved bows and socketed arrows,
they fought under commanders as a disciplined military force.
They raided Chinese villages
and plundered the growing trade between East and West,
and no one could stop them.
The Xiongnu was the migraine of the ancient world for the Chinese.
They simply just kept coming and they would not stop.
The Xiongnu wanted the finest material goods produced by the Chinese.
That is why they raided.
Imagine you're a villager in China and these men come from nowhere.
They come from over the hill without warning,
tearing into your village.
They shoot the headman, they shoot your husband.
They chase the women out.
There is no hiding place and there's a flurry of dust and arrows.
They're in and they're out and they take the stuff and they go.
China sent its military might against the Xiongnu.
The famed Terracotta Warriors
reveal the size and power of Chinese armies.
But the Chinese fought on foot and from chariots.
Not effective against hit-and-run cavalry.
A Chinese courtier wrote that the Xiongnu moved like a flock of birds over the land,
impossible to control.
Once mounted warfare really became deadly and effective,
it became a real problem.
If you're a farmer, the nomads know where you're going to be all the time.
Your house is in the same place 12 months of the year,
and when your crops become ripe, you have to harvest,
and the nomads know when that season is.
Whereas when you're trying to strike them back,
it's impossible to know where they're going to be
or when they're going to be there.
You have to search to find them.
To beat the Xiongnu, the Chinese needed soldiers who could fight like them.
They needed cavalry.
There are manuals of warfare that were written
to instruct Chinese warriors
on how to counter the tactics and the methods of the Xiongnu.
Those manuals introduced the idea of cavalry
to the Chinese military.
The Chinese military had not really used cavalry
before about probably 350 BC.
Chinese military, at first with some resistance
from the old aristocratic families, said:
"Well, my father fought on a chariot,
"and his father fought on a chariot,
"and I'm gonna fight on a chariot in my long robes like my ancestors."
But it wasn't long before Chinese warriors
traded their traditional long, flowing robes
for shorter tunics that didn't get in the way of fighting on horseback.
Eventually, the practicalities forced them to get rid of their robes,
to put on riding trousers,
to learn to shoot the bow on horseback,
and they, too, became a mighty horse archer force.
Chinese cavalry became experts at shooting the recurved composite bow,
and a lethal Chinese weapon, the crossbow.
While its cavalry trained,
China agreed to Xiongnu demands for payments of money and silk
until the year 133 BC,
when Emperor Han Wudi refused to pay.
And sent his army to attack the Xiongnu.
Chinese cavalry defeated the nomads.
And China seized new territories in the steppes,
pacifying trade routes and opening new horizons.
On one hand, we have this perpetual conflict
— in Chinese culture would be the Xiongn and the Han Chinese
that created incessant warfare.
On the other hand, it is this conflict
that demolished physical boundaries.
Even territory boundaries were constantly being pushed farther,
pushed back between the two forces.
This was a stimulus for exchanges,
for political changes,
for new ideas, for artistic traditions.
It was also a new era for the Silk Road.
A fortune in Roman gold traveled east
in exchange for Chinese silks.
And the Central Asian kingdom of Kushan
made its own fortune selling another luxury to China:
jade.
Silk Road caravans passed through this border station
on China's western frontier.
So many of them carried Kushan jade
that this station became known as the Jade Gate.
Chinese aristocrats coveted jade for its beauty
and something more.
They believed that jade would keep them alive forever.
The ruling elite commissioned jade burial suits
to preserve their bodies in the grave.
They believed that, upon death,
all the orifices should be plugged in
to preserve the spirit inside the person.
And this notion of jade
as a material with protective power in the afterlife,
is further enhanced by the fact
that they built an armor
made of thousands of pieces of jade.
And of course, if you're the emperor,
your jade armor would be made from the finest jade
from the western regions.
During the Roman empire, Silk Road trade flourished
as Chinese, Persian, and Kushan armies
kept the trade routes open across Eurasia.
China had leveled the battlefield
with nomad raiders from the steppes.
But Central Asian horse archers
were about to carve their names on History.
In the 4th century CE., Europe was invaded by a Central Asian people
whose name still evokes barbaric cruelty.
The Huns, who fought their way West, all the way to Rome.
European peoples like the Goths and Visigoths
— the so-called barbarians —
fled before their onslaught,
and sought refuge in Roman territory.
When the Huns withdrew from the Roman world,
those barbarian refugees stayed.
And the rest is History.
The western Roman empire was plunged into chaos
as barbarian tribes, dissatisfied with their lot,
rebelled against Roman authority,
and weak Roman emperors failed to crush them.
As Rome declined, migrating horse archers, called the Avars,
carved their own country out of eastern Europe,
bringing with them another Asian military innovation:
the stirrup.
This Chinese statue from the fourth century CE,
is the earliest known depiction of stirrups.
Some 300 years later,
an Avar horseman was riding with these stirrups
across Hungary.
By the eighth century CE,
the stirrup had spread from one end of Eurasia to the other
and mounted warfare was entering a new era.
The importance of the stirrup
relates to what kinds of weapons can you use from horseback,
and it made it possible to use certain kinds of weapons from horseback
that you couldn't use without stirrups.
Those weapons are the long sabre.
You have to lean over and absorb shock,
if you're going to use a long sabre in battle.
And the stirrups allow the rider to absorb the shock of contact
with a stationary target.
The other big weapon that was possible with stirrups
was a seated lance held under the arm.
You could stab somebody with the lance and then remove it,
riding past them without stirrups.
But if you seated it under your arm and used the lance as a shock weapon,
it would knock you off the back of the horse
if you didn't have stirrups.
So stirrups made it possible to use long swords and lances
as shock weapons against stationary targets
and keep your seat.
And of course that made it possible to have really heavy mounted warriors.
Now, the rider becomes a unit with the horse.
He's so anchored with his stirrups, anchored with this,
and then with his long lance
he becomes a single projectile unit.
Man, horse, saddle, lance, all locked together for the impact charge.
This was the age of the medieval knight.
A medieval knight's power
came from combining the Asian stirrup and the ancient shock tactics
of the Persian cataphract with a European invention:
articulated plate armor.
Strong enough to protect the wearer from sword and lance thrusts
while light enough to allow him to move freely on horseback
and on foot.
Heavy cavalry had never been a more potent weapon of war.
Medieval mounted warfare could be warfare
that generated a lot of force on the rider,
a high impact warfare.
In that case, the mounted warrior is being used
really as a shock weapon to strike the enemy.
But even Europe's formidable mounted knights
would be outfought by Central Asian cavalry
that burst out of the steppes and changed the world.
The largest conquest empire that the Earth has ever seen
was created by pastoral nomads from Central Asia.
In the 13th century,
the Mongols conquered as far West as Poland
and as far East as the Sea of Japan.
Mongol armies combined the devastating shock tactics of horse archers
with a highly sophisticated military organization.
They could gather quickly and march to distant battlefields.
Then the cavalry could reach the enemy's battlefield
before they set up defenses
which could deter their enemy psychologically and strategically.
It is said that the cavalry came suddenly
like something falling fro the sky.
and disappeared quickly
leaving no trace at all.
Western, especially European historians,
wrote that the Mongols appeared far away like several spots
but would suddenly gather before you, like dark clouds.
Unexpected attack was the core
The Mongols have gone down in History as bloodthirsty killers,
but they were also sophisticated, open-minded,
often generous conquerors.
They pacified the Silk Road.
Trade between West and East
flourished under this Mongol-enforced peace,
the Pax Mongolica.
Before the age of Pax Mongolica,
banditry was a very serious problem for traders,
for caravans, along the Silk Road.
The reputation of Genghis Khan and his descendants
created peace and safe passage along the Silk Road
because bandits were so afraid of the Mongol soldiers.
The Pax Mongolica,
the control of trade and exchange
that was made possible under the Mongols
connected China with Europe and with the Near East
in a really close way for the first time in world History
And that had a profound effect
on the development of European civilization.
Protected by the Pax Mongolica,
and anxious for good relations with the Mongol empire,
Europeans began traveling East as never before.
Merchants, missionaries, and diplomats
flowed East along the trade routes,
bringing back popular Asian goods like cloth and spices
and tales of the wealth and wonders of the East,
some true, some fabulous, but all fascinating.
From Europe to China,
Silk Road trade spread new knowledge of far-away lands.
The Silk Road made human beings realize
that there are other people out there,
and it opened the eyes of the East and the West.
The Italian cities of Venice and Genoa reaped huge rewards.
Their merchants traveled safely throughout Eurasia
and founded trading posts on the Black Sea
to receive and pass on Silk Road goods.
Their Silk Road profits funded magnificent art and architecture.
But their competition frequently plunged them into war with one another.
In one of these wars, Genoa captured a prosperous Venetian merchant
named Marco Polo.
Imprisoned by the Genoese, Polo dictated the story
of his Silk Road journey to China to a fellow prisoner.
Today, experts debate whether Marco Polo really visited China
or was simply retelling stories
he heard from fellow Silk Road travelers.
But there's no debate that "The Travels of Marco Polo"
was one of the most influential books in all of human History.
It tantalized Europe with tales
of China's immense wealth and advanced civilization.
And years before Marco Polo was telling those tales in a Genoese prison,
a Chinese invention was making its way across Eurasia to the West.
Something created centuries earlier
when an experiment ended very badly.
Ancient Chinese alchemists prepared potions of lead or mercury
for their aristocratic patrons
who believed that drinking these metals would help them live forever.
Instead, those concoctions killed them or made them insane.
Another deadly combination was sulfur
heated with an organic nitrate found in soil throughout China,
known today as saltpeter.
When alchemists experimented with this formula,
it burst into flame,
injuring the alchemists,
(Explosion)
and burning down their laboratory.
From that disaster was born a chemical mixture like none other.
It may have failed as an elixir of immortality,
but it would prove to be a potent agent of death.
This Chinese Buddhist scroll dating from around 950 CE,
depicts demons surrounding a seated Buddha.
One demon holds what the Chinese called a "huo quiang", or fire lance.
It's the earliest known image of a weapon
powered by that deadly mixture of saltpeter and sulfur.
Known to history as gunpowder.
In the early 13th century,
the Mongols attacked China's Jin Dynasty.
The Jin Dynasty's army fought back with exploding gunpowder bombs.
But as the Mongols conquered more and more of China,
Han Chinese artillerymen joined their armies
and marched West, bringing their gunpowder weapons with them.
The Mongols attacked Russian and Polish cities
with exploding fire bombs.
And Europeans found out the hard way what gunpowder could do.
By the end of the 13th century,
the formula for gunpowder was known as far West as England,
and Europeans were inventing their own versions of the new weapons.
It wasn't long before this Chinese invention changed European history.
On 26th August, 1346,
near the village of Crecy in northern France,
the armies of France and England prepared to fight.
Mounted on their war steeds, encased in their armor,
the flower of French nobility formed their battle line,
while the English deployed a very different force.
Thousands of expert archers.
The French sent their higher Genoese crossbowmen to attack the English
before French knights annihilated them.
But the English king, Edward III,
had spent years training his longbow men.
And all that training was about to pay off.
Nothing like this had been seen on a western battlefield up to this time.
The first time that a volley of arrows was unleashed by the archers at Crecy
would have represented something completely new
to many of those in the French army watching it.
A cloud of arrows descending towards them.
It would have been frightening,
and of course the effect was almost immediate.
Showered by English arrows, the Genoese turned and ran,
and according to medieval accounts of the battle,
they were also panicked by another English weapon.
Giovanni Villani, writing very soon after the battle,
says in his chronicle that so loud and intimidating
was the noise created by the guns
that they thought God was thundering.
"The English guns cast iron balls by means of fire.
"They made a noise like thunder
"and caused much loss in men and horses."
Noise like that would have been unprecedented
to the soldiers on the battlefield.
Nothing in their lives could have prepared them
for a a bang of that size
and accompanied by smoke and acrid sulfur smell,
which would hang in the air.
The impact of which, of course, they couldn't see
until men around them dropped.
Not even professional soldiers like the Genoese
would have experienced anything like this before in their lives.
That would have been terrifying,
and it's no wonder that they scattered and ran.
They turned and fled into the face of the oncoming French cavalry charge.
The French cavalry were now coming onto the battlefield
and they were appalled
at these people they'd hired running away.
And they cursed them and they rode into them,
and as many Genoese fell to French hooves
as they did to English arrows and gunshots.
And the French knights, all 12,000 of them,
double the size of the English army,
they came charging down onto the English.
And they, too, fell to the English arrows and the English gunshot,
and they came again and again and again.
15, 16 times, they came.
And their horses were ripped to shreds
and the men were thrown from their horses.
And those that weren't thrown,
they had the opportunity that the dagger men rushed in
and they brought these knights down.
This was a moment in History where the world changed.
It spelled the beginning of the end for the medieval knight.
The Battle of Crecy has gone down in history
as one of the earliest uses of gunpowder weapons
on a European battlefield.
Some 500 years after,
it burned down a Chinese alchemist's workshop,
gunpowder had become destiny's weapon of choice.
After Crecy, it was only a matter of time
until the fates of peoples and nations were decided by the gun.
Within two centuries,
Europeans would use their powerful gunpowder weapons
to dominate the world,
creating empires that would evolve into today's global trading culture,
which binds people together by commerce instead of the gun.
But before Europe could embark on its empire-building adventure,
its medieval social order
would be shattered by a catastrophic event.
One that would forge a new Europe in a crucible of horror.
While guns thundered at Crecy,
something else was spreading along the Eurasian trade routes.
Something that would kill tens of millions of Europeans.
An apocalyptic destruction of human life
that would lay the foundations of the modern world.
At the Battle of Crécy in 1346,
the English won an historic victory over France,
helped by a Chinese invention that had traveled to Europe.
Gunpowder.
And in the same year of 1346,
some 2,000 kilometres east of Crécy,
another battle was taking place on the shores of the Black Sea.
A Mongol army had been laying siege to the Crimean port city of Caffa,
a Silk Road trading post belonging to the Italian city of Genoa.
The Mongols were masters of siege warfare.
But Caffa was still holding out after more than two years.
Suddenly, the Mongol army was decimated.
Not by Caffa's defenders, but by an unknown disease.
The Mongols quickly ended their siege.
But before they left Caffa,
they loaded their siege engines with the corpses of their dead
and flung them over the city's walls,
believing that the stench of death would kill the defenders.
Medieval chronicles say
that Caffa's defenders did die by the thousands,
but not from the smell of death.
One year later, in 1347,
the same disease that had killed the Mongols at Caffa
was killing people in Constantinople.
By 1348,it was killing people across Western Europe.
By 1350, it was killing people as far away as Greenland.
And terrified Europeans had given it a name.
The Black Death.
In just under a decade, from 1347 to 1356,
the Black Death killed a t least 25 million Europeans.,
one third of Europe's population.
Today, most scholars believe
that the Black Death was an outbreak of bubonic plague.
that was transmitted to humans by infected fleas living on rats.
And we believe that it spread across Eurasia
by hitching a ride with armies, ships, and caravans
along trade routes that were already ancient
by the time of the Black Death.
Micro-organic travelers of all kinds
have moved across Eurasia for thousands of years.
A bio-migration that has had as big an impact on history
as the more famous exchanges of new technologies and luxury goods.
And as a recent discovery shows,
tiny living things moving along the Silk Road
brought life as well as death.
We were putting together some new methods
of looking for early agriculture,
and for that we needed to do a survey
of all the finds of early crops in Europe.
When you looked at a map of all of Europe,
then you could see there were these Chinese crops
in small numbers very early on in Europe.
"Very early on" was around 2,000 BC,
when a Chinese grain called broomcorn millet
appears in the Eastern European archaeological record.
The actual crop itself will decay or be eaten,
but rather fortunately,
if it's cooked and over-burnt, it turns to carbon.
That will stay in the archaeological record for a long time.
In the Chinese province of inner Mongolia,
archaeologists are studying the origins of broomcorn millet,
one of the world's oldest domestic crops.
We are looking at a broomcorn millet field of almost 16 acres
The cultivation of broomcorn millet in this place
dates back to nearly 8000 years ago.
It's the earliest area of human-cultivated broomcorn millet in the world.
After broomcorn millet's birth in this place,
it spread to the West from the East.
It spread to Europe.
Since it originated from the East and then spread to Europe,
it can be regarded as an important contribution
of our Eastern civilization to the Western counterpart.
But it isn't clear just how and why
broomcorn millet travelled thousands of kilometres across Eurasia,
through some of the world's harshest environments,
all the way to Europe.
Millet's long journey may have begun simply because it travelled so well.
Millets are essentially cereals, but they're very small.
And because they have very small grains,
they're hardy and they're tough,
and they can grow quite fast.
Broomcorn millet, at a push,
can get from seed to seed in 45 days.
You can plant a seed in the ground
and 45 days later, in the right conditions,
you may have plants.
That's incredibly fast.
So, if you're moving around parts of Asia,
where, on the one hand, there's a long winter,
a short growing season,
and you can't particularly r ely on rainfall,
then something that gets a move on in terms of its growth cycle
is very valuable.
There are accounts of communities that are on horseback
for quite a lot of the time and herding animals and so forth,
but for that short season of the year
that millet grows in,
they can actually sow the millet on horseback,
trample it in with the horse's feet,
and then either leave a few teenagers there
to scare the birds off for a couple of months,
come back two months later, and harvest the crops.
Millet was a highly mobile grain,
but there wasn't any evidence
of how it might have travelled from its home in northern China.
Until archaeologists found signs of millet cultivation around 2500 BC
in the foothills of the Tian Shan Mountains in central Asia.
At that point we asked ourselves,
"Well, what is it about these foothills?"
You know, "Why the foothills?"
Clearly, it's about water.
If one travels across the centre of Asia,
one realizes why water is a key.
And wherever you are in Asia, it can be very dry, of course.
But if one goes uphill to those foothills,
then one has somewhere
where there will be streams running off the mountains and water.
Archaeologists found that around 1,000 BC,
millet farmers left theTian Shan foothills
and their reliable water supply
and began moving into much harsher environments.
We can see the confidence of farmers
spreading out from where the water is really safe
to areas where you have to know more
about the water and the landscape and the geography,
both into the steppes to the north and to the desert to the south.
Millet's local migrations may have linked it with the world.
Migrating millet farmers in search of water
may have settled near trade routes.
And long-distance travelers would have chosen routes
near reliable sources of food and water.
I think very much those traders are definitely working
through networks that are already centuries old.
It's at least a millennium before you see something crystallizing
that you can start calling the Silk Road.
Another discovery has revealed that this ancient grain migration
wasn't only from East to West.
Wheat was transmitted from West to East,
arrived in China and was accepted as our main staple.
This reflects the transaction between Eastern and Western cultures.
The Eurasian steppe, acting as a route
for early exchanges between Eastern and Western cultures.
is the predecessor of the ancient Silk Road.
Ethnic migration, the fusion of cultures,
and the flow of trade are ll embedded in this road.
Trading millet and wheat between China and Europe
may have done much more than feed people.
It may also have enabled profound social change.
Seeds germinate at one time of year
and are harvested another time of year,
and that's kind of hardwired into their biology.
And so farming is a one-season activity,
and there are things going on at other times of year.
And during the second millennium BC,
a number of societies are doing something
which is quite radically different,
and that is putting more than one season in a single year.
Crops like millet are really useful for that,
in that if you are a western farmer,
with wheat and barley fields
reaching maturity during the summer,
and you think
"Right, with the same plot of land, "I want to increase production.
"And so, I want another crop after I've harvested the first crop."
You can't do a long season, large-grain crop
like wheat and barley again,
so, something that's short and sharp like millet
you can tag on to the end of it
and catch another season before the winter's set in.
Interestingly, when you get to China, it's the converse.
You have this short season crop already there,
and by rearranging your life,
you can bring a long season crop such as wheat and barley in at that stage.
So the implications are, with the same plot of land,
you could basically get two harvests rather than one.
So, two sets of calories rather than one.
It may release some of the community to not farm at all
and occupy roles within cities, or as craftspeople, or leaders.
If we look at the second millennium BC,
what we certainly see
is at the same time as multi-cropping is there,
then there are a lot of the community,
are not farmers, but instead metalworkers,
or kings, or priests, or something else.
And so what we see evidence of
is multi-cropping allows a non-farming sector within the community.
So, what we have is a small, not very impressive-looking seed,
but because of the way it grows and because of its biology,
it has a massive impact
in changing the productivity
of the heartlands of western farming.
So, those western farmlands could, in the same area,
produce two crops rather than one,
and that enabled a whole series of things
that we associate with the word "civilization."
Finding Chinese millet in Europe and European wheat and barley in China
suggests that long before the Silk Road,
East and West were introducing one another to new foods,
and that the movement of crops
may have helped create the earliest East-West trade routes.
And in the deserts of far western China,
archaeologists have discovered another way
living organisms could travel the Silk Road.
This is Xuanquanzhi relay station,
an archaeological site near the town of Dunhuang,
a major stopping point on the Silk Road.
2,000 years ago during the Han dynasty,
Xuanquanzhi was a very busy and very cosmopolitan place.
According to records written on bamboo and wood
unearthed from Xuanquanzhi
Xuanquanzhi was not only serving as a relay station,
but also as a place to receive caravans and government officials.
During the Han Dinasty, the major officials received here
included the king of Kholan Kingdom from the Western Regions,
the king of the Wusun, also called the Issedones
and the king of the Kangu, also called the Sogdians.
At most, the number of received guests would be over 1000.
Therefore, this place was filled up with a mixture of people from all regions.
It would be used for merchants,
and it would also be used for government business.
People could travel long distances
knowing that there was somewhere they could stay
be refreshed and recover, change their horses,
and then move on to the next relay station.
The wonderful thing about the Xuanquanzhi trading post
was that it's in a part of the country that is not built up now,
and the environment, very, very dry and often very cold in the winter,
means that things are preserved there very well.
So, a lot of the things - inside that trading post -
have survived instead of decomposing.
Excavators were especially excited to find something
that perhaps only an archaeologist could love:
the 2,000-year-old equivalent of toilet paper.
In China, they wrote back, in the Han dynasty times,
how they would have a stick with cloth wrapped on the end
for people to wipe themselves with.
There were quite a few of these sticks thrown into the latrine
as if people discarded them in there when they'd finished.
These sticks have been found at some other excavations in China as well
but what's great about this relay station
is we still have the cloth wrapped on the end
and we still have the human faeces on.
So, we scraped off the dried faeces from the cloth
and took them to the lab.
We found four different species of parasite
in those who used this latrine.
Two of the species are spread by faeces
contaminating your food or your hands or your drink:
roundworm and whipworm.
Another species was a kind of tapeworm
that they probably acquired by eating raw or undercooked pork.
And then, we found the really exciting find,
which was the Chinese liver fluke.
This is a small flatworm
that lives in eastern and southern China and in Korea.
It can only survive in marshy, wet places.
But here, we found it 1500 kilometres away from anywhere that has it in modern times.
So, it wasn't what we expected to find.
It was brilliant that we could find it on the Silk Road.
The liver fluke requires a lifecycle
where it passes through freshwater snails,
and through small fish and then, bigger fish.
If you cook the fish, then you don't get the liver fluke.
But if you eat the fish raw, then it hatches out in your stomach,
migrates through your body, crawls into the liver,
and then develops there.
There was no way that people in the area of this relay station
could have caught it in that particular area
because it was far too dry.
There were no lakes.
There were no freshwater snails and fish for them to infect.
The discovery of the liver fluke is of great importance.
It indicates that the caravans or government servants
brought their excrement, as well as diseases ,here
over thousands of kilometers of travel to this place, Xuanquan station.
With state of the art overseas analysis,
we are comparing it with similar evidence originating in Europe.
to figure out whether the liver was spread
from China's eastern coastal area to Europe
or if it was spread from Europe to China
or if the disease spread between these two areas.
We are doing some further research.
The finds at Xuanquanzhi have shown
that humans could carry diseases long distances along the Silk Road.
Another discovery has revealed what could happen when they did.