01x01 - Secrets of the Great Wall

[bunniefuu]

Allan: Inner mongolia, china.

I'm here on the trail of

a 750 year old legend,

that began with

tales brought home,

by an intrepid

european explorer.

The main reason I've come

here is because of this book.

These are the accounts of

the travels of marco polo.

"there at this place is a

very fine marble palace.

The rooms of which are all

gilt and painted with figures

of men and beasts and

birds all ex*cuted with

such exquisite art,

that you will regard them with

delight and astonishment."

what he's talking about here

is the great fabled city of

kublai khan, the

grandson of genghis,

xanadu.

Now with the help

of new technology,

I'm out to discover if marco

polo's descriptions of such an

astonishing city

can really be true?

I'm allan maca.

An archaeologist and expert

in ancient civilizations.

And I'm investigating

china's distant past

from a whole new perspective

Space!

Today, state-of-the-art

satellites see the world

in stunning detail.

And reveal hidden archaeology,

enabling us to recreate a lost

ancient world,

invisible to the naked eye.

Working alongside

leading chinese experts,

my team and I are traveling

to some of the country's most

remote and

incredible landscapes,

and with cutting-edge science,

investigating previously

unknown cultures, lost cities

and devastating cataclysms.

This is ancient china as

you've never seen it before.

The vast steppe

of inner mongolia.

An open grassland in one

of the largest and least

populated regions of china.

And, if marco polo

is to be believed,

this wide-open wilderness once

contained one of the greatest

cities on the planet.

Two centuries before columbus

sailed for the americas,

marco polo travelled from

europe along ancient trade

routes, to explore the

distant lands of the east,

keeping detailed

journals as he went.

In 1275, he arrived at

the gates of a great city,

kublai khan's xanadu.

Today, the only clues

left on the ground

are a series of mysterious

mounds rising from the plains.

There's just a lot of grassland,

just a lot of empty space,

it's hard to imagine that

there could ever

be a city here.

I've been hearing

about xanadu all my life.

As an archaeologist I've

studied and taught these

periods but I've

never been here.

Now I'm going to

explore the mystery

of xanadu in a whole new way.

Wow. Amazing!

Ryan: Yeah it

really sort of pops

Allan: With

cutting-edge technology,

can we bring this legendary

city back to life?

Look at this thing.

This is a wild image!

Scouring china for clues,

what can we discover about the

man who ruled over a quarter

of the world's population?

Jenny: This is much

bigger than I expected.

Allan: And how was beijing,

one of today's

great megacities,

born from xanadu?

I think we'll get a great

point of view from up here.

What an expanse.

Close up, it's clear

these mounds are man-made.

Sighting straight down

this east-west wall-line.

It's a perfect

90 degree angle.

This is cool.

But could xanadu

really have been as

magnificent as

marco polo described?

A great medieval city filled

with astonishing architecture

and lavish palaces?

Down on the ground, these

ruined walls don't tell us much.

But from space, 500 miles up

The shape of this lost

city is revealed.

The remains of a

series of massive walls.

Each one guarded by gates

and corner watchtowers.

The outer wall runs for 5 and

a half miles enclosing an area

at the time, even

bigger than london or paris.

And right in xanadu's

center, the faint

outlines of buildings.

Chinese archaeologists have

surveyed and excavated this

central area, but since

becoming a protected site,

further digging is restricted.

Yet, there are other

ways for us to investigate.

Researchers ma he, xi

yaqing and ma qinglong

from peking university

are being joined by eric lo

and ryan kastner from

my tech team.

Together, they'll use hi-tech

sensors on drones to conduct a

whole new survey

of central xanadu.

Eric: So what I'm putting

on is a multispectral camera

which sees in other

bands beyond the visible

red, green and blue

that we normally see

and we're hoping

that this will

see some anomaly,

that might indicate

there's been a structure

there in the past.

Allan: While the

multispectral camera looks for

signs of buildings

beneath the surface.

A second drone captures

hundreds of images to create a

detailed 3d model of

everything above the ground.

Hey what's up guys?

With the results in,

I'm going to take a look with

xanadu expert, bao lige.

What have you got?

Ryan: With the drone imagery

you can see a tremendous amount

more detail than you can see

with the satellite imagery.

So you can see some

of the structures and

obviously the roads.

Allan: And elevation data

from the second drone,

reveals every slight

bump on the ground.

Oh neat, wow! Amazing!

Ryan: Yeah,

it really sort of pops.

Bao: Look at that,

it's really really clear!

Allan: And look at

all these buildings,

I mean there's a

lot going on here.

Ryan: Yeah you can clearly

see a bunch of different

types of structures.

Allan: Straight lines

mean man-made structures

like walls and roads,

and boxes give us the

outlines of buildings.

Revealing these

features in the central zone,

combined with historical

records allows us to recreate

the very heart of xanadu.

A dense concentration of

streets and buildings.

Most prominent of all,

three mighty structures.

Chinese experts have

identified these as

kublai khan's palaces.

Bao: This whole palace

city is arranged along

the central axis,

it's a very

well-established layout.

Allan: The largest palace

is in the north,

this was the mu qing ge,

kublai khan's residence

and a place for official

business and banquets.

There's little known

about how it looked,

but chinese archaeologists

have discovered elaborate roof

ornaments and beautiful glazed

tiles that give us a glimpse

into its magnificent past.

From these grassy mounds,

technology is revealing that

marco polo's descriptions

could really be true.

But why is xanadu here at all,

in the middle of this

remote wilderness?

The city was built by kublai

khan from scratch in 1256.

He was the grandson

of one of history's

most famous warlords,

genghis khan.

50 years earlier, genghis khan

had united the nomadic tribes

and established a

vast mongol empire,

including conquering

most of the dynasties that,

back then, ruled china

and taking control of their

largely han

chinese population.

But the south, ruled by

the southern song dynasty,

remained unconquered.

After genghis khan, the

empire was divided into

mongol kingdoms called khanates

and in 1251 kublai khan took

charge of what today,

is inner mongolia.

He was determined to establish

a new dynasty that he'd call

the yuan, defeat

the southern song,

and bring all of china

under his rule as one

all-powerful emperor.

But first he needed a

secure base from which

to unleash his campaign.

The city of xanadu was born.

I've seen how the center of

xanadu was full of palaces.

But what lies beyond

these inner walls?

To find out, we need to go

back to the satellite images.

Archaeologist sarah

klassen, from my tech team,

is taking a closer

look at the wider city.

Sarah: I can see quite a few

faint impressions on the land

that might be related to

archaeological features like

streets or buildings.

Let me see if I can

enhance this image.

Oh wow, look at this,

this is pretty neat.

Allan: Using infra-red,

sarah can spot differences in

how the vegetation's growing,

that indicate

man-made structures,

hidden just

beneath the surface.

Sarah: So all of those faint

impressions that I saw before

are now very

visible on the landscape.

Allan: These infra-red

satellite images

combined with chinese

archaeological evidence and

historical records, reveal the

whole walled city of xanadu in

stunning detail.

Not just its palaces,

but hundreds of buildings.

Courtyards and compounds.

Defensive towers

and grand gateways.

An incredible megacity.

Marco polo's descriptions

are so far proving right,

but there's a mystery, because

he described another palace

that doesn't show up.

With a golden roof

and lacquered pillars,

experts believe it was a

vast circular building.

Just what was it?

And can we find it?

Lost circular palace that

marco polo said was one of the

wonders of xanadu.

Could its circular shape

indicate a special type of

mongol building

that's still in use today?

I've been invited by enkh bayr

and his family to help out

building a traditional

mongolian house, a ger.

You can see that it's

a latticework pattern

made from willow tree.

And these are thicker

willow posts that hold up this

central structure, that

also can have a slight opening

because of course, there's

going to be a cooking fire in

here as well, and then

you'll sleep over here

on the other side.

These simple round

structures are

the key to a

nomadic lifestyle;

light and easy to assemble,

they're quick to pack up and

move on to new pastures.

Enkh: I've grown up in mongolian

gers since I was a child.

I feel very

comfortable sleeping in one.

They are

well-ventilated and very cozy.

Allan: This tough

nomadic culture is the world

that kublai khan came from.

Could his mongol roots shed

light on one of marco polo's

most vivid descriptions?

He says, "the whole palace

is built of these canes.

The construction of the palace

is so devised that it can be

taken down and put up again

with great celerity and it can

all be taken to pieces and

removed withersoever the

emperor may command.

When erected, it is braced

against mishaps from the wind

by more than 200

cords of silk."

so imagine the

size of this thing.

Could it have been a ger?

A monumental ger?

An imperial sized ger?

Now, using marco polo's

description and

other historical sources,

we can recreate what

kublai khan's palace of

canes might've looked like.

Look at this thing.

This is huge!

This is a wild image.

Circular like a ger,

with a varnished golden

roof made of bamboo canes.

It would've been supported by

lacquered and gilded pillars

decorated with dragons

and stood as high as a

ten-story building!

This moveable palace

hosted lavish banquets

for over 2000 guests.

Even after more

than 750 years,

surely something this huge

would have left some trace.

If our drone images

failed to detect it,

would it help to

look from space?

Sarah: When I look close at

the palace area I can see a

ton of features on the

landscape and even kind of

beyond that until the

second city wall.

And the northwest is

really interesting

'cause I don't really see even

faint impressions of

archaeological features.

I would've thought that this

whole area within the city

walls would've been taken up

with buildings and streets.

Allan: This large

empty space seems strange,

but during the years he

spent at kublai khan's court,

marco polo said he

saw a great park,

stocked with wild animals,

to satisfy a favorite mongol

pastime, hunting.

And he wrote that the cane

palace stood in a grove within

these hunting grounds.

Guided by the

satellite imagery,

the drone team moves in

to take a closer look.

Ryan: We think we might have

found something interesting

in the outer city.

You can see

Allan: Oh yeah, oh yeah!

Ryan: Yeah it's

Allan: Most of xanadu's

structures were built

on platforms to keep

them clear of wet ground.

If a base had also been

laid for the cane palace,

it might have left

a circular trace.

We walked all over this;

we didn't see that

from the ground at all.

Ryan: Yeah it's hard to

actually see any of this

stuff, that's why the drones

or the bird's eye view really

gives you a nice perspective.

Allan: Well the

east side of this thing

very clearly looks

like half of a circle.

Ryan: Yeah.

Allan: It does, it

definitely does.

Could this really be it?

A faint impression of kublai

khan's amazing cane palace?

Allan: I'm hunting for

evidence of one of

the great lost

wonders of xanadu.

A vast moveable palace.

And my tech team

has found something.

Ryan: This is the

digital elevation model,

so the colors

indicate the height,

how high or low, off

the ground these are.

Allan: Could this be the

raised platform that my

team is looking for?

Ryan: It's indented so it's

a little bit more red here,

so you can see it's

a depression, it's a

crater of some sort.

Allan: Yeah very clear.

Ryan: Yeah it's a very

clear depression.

Allan: Sadly, it's not

the relic of a raised

platform, but mr. Bao

has another theory.

Bao: For this kind of

palace, maybe they lifted

the whole platform

up and away on wooden poles.

Or it was a large-scale

imperial carriage with a

temporary palace on top.

Allan: If mr. Bao is right,

kublai khan's

amazing golden-roofed,

imperial ger, really was a

temporary structure with no

permanent base, in true

nomadic mongol style.

So for now, exactly where

it stood remains a mystery,

but the satellite data are

revealing other secrets.

Sarah's spotted

something even further out,

past the hunting

ground and the outer walls.

Sarah: If I look

beyond the walls,

of the city, I can see

some faint impressions.

Take a look at that.

So, there are actually

buildings and roadways that

extend beyond the

walls of the city.

Allan: If these date to

kublai khan's yuan dynasty,

then xanadu even stretched

far beyond its city walls.

And out in this

wider sprawling city,

huge, intriguing structures.

I'm heading east beyond

the outer city walls to

investigate, with

xanadu expert, bao lige.

Bao: We are at xanadu's little

east gate on the main road

that goes through it.

During the yuan dynasty this

eastern suburb served as a

place for the nobility to stay

when visiting the great khan.

Allan: It explains

the impressive walled

compounds revealed on

the satellite images.

And chinese research also

reveals there were sprawling

suburbs beyond the

city walls on every side,

with evidence of

military barracks,

markets and guesthouses.

And right on the edge of the

suburbs there are also two

enormous and

identical structures.

What are they?

So we've got some really

interesting buildings here.

What do you know about

it, what can you tell us?

Bao: In the yongle classics,

it's recorded that xanadu had

two granaries, one in the

west and one in the east.

They measured 150 meters

wide and 290 meters long.

Allan: That's the size of 10

american football fields.

Bao: There wasn't anything

else on this scale in other

areas, or here in

the eastern suburb.

Allan: All the evidence

points to this being

one of xanadu's

vast grain stores.

To explore it in detail,

the peking university

tech team gets to work.

Can we look really closely

at this area you scanned?

Oh wow!

Ryan: You can clearly see

the different structures.

Allan: Combining

our scans with historical

records, reveals this granary

isn't just one large barn,

it's an entire complex.

Bao: I think each different

type of grain would be

stored separately.

This big area in the middle,

you could call it a courtyard.

You could take out grain that

hadn't been used up and re-dry

it in the sun before storing.

Allan: Now, knowing

the layout of this

granary, can our scans help

solve an enduring mystery.

Just how many

people lived in xanadu?

S of a granary

far outside xanadu's city walls,

to see if it can

answer a crucial question.

I'd be really interested

if we can come to

some sense of what was the

population of the city at that

time, by estimating

volume of grain storage,

against what people

would have needed.

Bao: At that time, each

person would have needed

180 kilograms of grain per year.

Allan: Using our

model and chinese research,

we can now estimate

how much grain this

granary could've held.

Eric: Based on these

calculations we could store

21 million kilograms and so we

can see that we'd have an

approximate population that we

could feed of 120,000 people.

Allan: Wow, that's

really substantial.

If you consider that london

in the 13th century only had

about 80,000 people that

says that this was a really

substantial city.

Even though these

figures are based

on rough estimates, they're

for just one of two granaries

at xanadu, which would mean

the potential population could

be more than 200,000 people.

Almost twice the size of marco

polo's home city of venice.

It's no wonder marco

polo was blown away

by what he saw here,

and he must have noticed that

unlike the winding streets

of mediaeval europe, xanadu

was built to a precise plan.

The city is aligned

along a north-south axis.

And even its location

was carefully chosen.

This was geomantically designed.

So it's laid out in

relation to geological

features of the landscape.

Protected by mountains

to the north and

with a river to the south,

this is an ideal setting for

han chinese city builders.

We have a city built here by

nomadic peoples from the north.

And it's incredible

that kublai khan,

as a hereditary

mongol emperor,

is using ancient chinese

principles to design his city.

Kublai even had a

han chinese advisor

draw up the plans, giving it

the square concentric walls

and central palace area.

This is a classic

han chinese city plan.

In building a

permanent walled city,

with a hunting ground

and imperial-sized ger,

combined with a

chinese layout,

kublai khan was embracing

both his mongol roots and

han chinese culture.

The question is why?

And was this blending of

cultures happening elsewhere,

beyond the walls of xanadu?

680 miles to the south west,

in the ancient city of xi'an,

a clue has been

discovered in a tomb that

could hold the answer.

Dr chao-hui jenny liu, our

expert in classical chinese

art and archaeology, is

meeting excavation leader

miao yifei and his team,

who are analyzing this

700 year-old work of art.

Jenny: Here it is, the mural.

(speaking mandarin).

Wow.

Allan: This mural once

lined the curved walls of

a lavish circular tomb.

Jenny: This is much

bigger than I expected.

This is amazing.

Miao: Once I'd properly

entered the tomb,

I was totally stunned.

This was so beautiful,

I was astonished,

really surprised.

Jenny: It's amazing.

Here you have six

people sitting on this,

sort of a bed with a

screen in the back.

And the center person, we

think it's the husband,

is wearing mongol clothes.

We see this kind of clothes also

on portraiture of kublai khan.

There's a white robe and

then this kind of red hat,

very typical of

mongol clothes.

Allan: But closer

inspection of these

traditionally mongol images,

reveals some surprising details.

Jenny: This is a hunting scene,

where the hunter is

sh**ting an arrow at the doe,

but there's a little man

underneath here, you see?

And he is milking the doe,

so it completely changes the

picture because a hunting

scene would be yuan dynasty or

mongol, but this story where a

good son milks the doe to give

milk to his parents,

that's a chinese story.

This mural shows that the mixing

of cultures chinese culture,

han culture, mongol,

yuan culture,

they become one, and

you cannot separate them.

Allan: It seems the

mixing of mongol and han

chinese cultures was not just

happening in kublai khan's city;

it was spreading

far beyond xanadu.

And this was all

part of his plan.

He knew he had

the military might to

conquer the rest of china

but to keep control, he'd

need to win hearts and minds.

It reminds me of something

that the legendary

chinese advisor of kublai khan

supposedly said to the great

emperor, he said,

"look you can conquer

a land by horseback,

but you can't administer

a land by horseback"

embracing both cultures was

kublai khan's key to success.

And this plan began

right here with xanadu.

They designed a city,

so that they could control the

population, keep them

happy and administer things.

Not in the way that

mongol horse nomads would,

but the way agricultural

han chinese would.

Xanadu was kublai

khan's power base.

And marco polo described one

building that was the very

heart of operations, a

palace called the da'an ge,

the pavilion of great peace.

The platform that we see

today is not the only

trace that remains.

Once stood at the

very heart of xanadu.

Only rare fragments of xanadu's

palaces have survived.

But in 2003 chinese

archaeologists unearthed

something astonishing.

Wow. Here it is.

This is the legendary

marble pillar from the

da'an ge palace complex.

Look at how big this thing is.

The carving is exquisite.

You have flowers here, which

are symbols of auspiciousness

and good fortune.

You've got the dragon.

Look at it, twisting around

all the way to the tail.

In han chinese culture,

the dragon is a symbol of

imperial power and typically

had 3 or 4 talons, but

this one is different.

So here we have five

talons and a smaller head,

smaller than we see in dragons

from earlier dynasties.

We have a horse nomad

asserting himself as a

great chinese emperor.

People looking at this, they

would have known that this is

kublai khan himself.

He is the dragon,

telling the world,

I am the head of a

new chinese dynasty,

the yuan dynasty.

Now, by combining recent

chinese academic studies

with our drone surveys

of central xanadu,

we can bring kublai

khan's magnificent

pavilion of great peace

back to life, for the first

time in over 650 years.

Woah, this thing was big!

Ah incredible,

incredibly beautiful.

I mean, there's no

question looking at this,

that the da'an ge was

a classically han

chinese building.

The da'an ge sat on a

raised central platform.

Supported by huge marble

pillars this great palace was

taller than a modern

22-storey building.

This was the site of

kublai khan's throne,

the "very fine marble palace"

that astonished marco polo.

I've explored kublai

khan's great palaces,

but the satellite images

also reveal other prominent

structures among the

hundreds of buildings.

Their layout suggests

these are not palaces,

but temples.

But mongols traditionally

practice shamanism with no

need for temples.

So what's going on?

Almost 900 miles

west of xanadu,

close to the city of zhangye,

jenny is searching for answers.

These sheer cliff faces

hold something very special,

an incredible complex of

ancient buddhist temples,

carved deep into the rock.

Buddhists started carving

these shrines centuries before

kublai khan's yuan dynasty.

But what then?

Throughout history, many

invaders wiped out the sites

and shrines of

existing religions.

But here at the

ma-ti grottoes.

Jenny: Wow, look at

all these niches!

Allan: Jenny's noticed

something surprising.

Jenny: The structure

of it, the archway,

this is largely of

the yuan dynasty style.

Allan: Everywhere,

signs that the carving

continued under kublai khan.

Jenny: The dress and

also the hairstyle,

the very peaceful, calm

expression on the face,

the lotus seat too is very

typical of the yuan period.

Allan: This shows

that buddhism didn't just

survive under

kublai khan, it thrived!

And back in

xanadu, li hailiang,

director of the xanadu museum

has evidence that suggests

this went far

beyond just buddhism.

Li: This artifact

is a tomb headstone,

it's got islamic

texts carved on it.

The yuan dynasty implemented

an all-embracing policy

towards all religions.

This kind of freedom of

belief was unprecedented,

so they could build lots of

temples in xanadu at that time;

buddhist ones, mosques,

nestorian christian churches

and so on.

So now we locals call

xanadu 'the 108 temples'.

It reflects very lively thinking

in yuan dynasty society.

Allan: Combining our scans

with historical records,

reveals that these two buildings

were buddhist temples.

But they were just two of

dozens of religious buildings

including mosques, daoist

temples and confucian shrines.

By design xanadu was a melting

pot where different peoples,

philosophies and

religions all came together.

A city every bit as

vibrant and cosmopolitan

as marco polo described.

From where, kublai khan could

now launch his master plan,

to conquer all of china.

Xanadu, became one of the most

important cities on earth.

Kublai khan was named

the next great khan,

with power over mongol

khanates that now reached from

today's far eastern russia,

all the way west to turkey

and ukraine.

But, he still needed to

was still to conquer the

southern song dynasty.

To achieve his goal, he

planned another city,

a second capital closer

to the chinese heartland.

Today, xanadu's sister

city, known as dadu,

lies hidden 170 miles south,

deep beneath the streets of a

very modern megacity.

Beijing.

Now home to over

20 million people,

it's more than twice the

size of new york city.

750 years ago, marco polo's

adventures also brought him

here, to the newly created dadu.

He wrote that it's

palace was so vast,

rich and beautiful that "no

man on earth could design

anything superior to it".

In 2016, the foundations of

kublai khan's palace were

discovered beneath beijing's

famous forbidden city,

lost traces of the

imperial heart of dadu.

Now sarah has come here to see

if satellite images can reveal

any more of kublai

khan's second capital.

Sarah: Oh wow, this

is really interesting.

Allan: About 5 miles

north of where dadu's

palace once stood,

sarah's spotted something,

an unusual line of trees.

Down on the ground, it

starts to make sense.

Sarah: Alright, so this is

what I've been looking for.

So we're on this large

mound, linear mound in

the middle of this city.

It looks like it's

definitely manmade.

You can see that

where I'm standing,

it's actually part of this

longer linear embankment and

it actually looks like it

forms a square around the city.

Allan: Chinese

research confirms,

this is part of an

original city wall of dadu.

Sarah: It's pretty incredible,

that something this old is

still in the middle of the

city of beijing and hasn't

been destroyed over

hundreds of years.

Allan: Adding this city

wall to the satellite image

along with data

from historical maps

reveals something amazing.

Beijing's modern streets still

align with dadu's city walls,

as if kublai khan's capital

was the blueprint for this

21st century city metropolis.

Sarah: So the similarities

between what we can see here

at dadu and what we saw

at xanadu are incredible.

Allan: Kublai khan had

taken the classical

chinese design of

xanadu, and supersized it.

Dadu was ten times bigger.

From dadu kublai khan could

strike out south and by

1279 he'd achieved his goal.

For the first time

in over 350 years,

the nation was reunited.

Kublai khan was finally

emperor of all china.

Kublai khan's incredible

vision allowed this mongol

ruler to found a new dynasty,

that was accepted by the

han chinese people

of his empire.

Under his reign,

china thrived.

He extended trade routes to

reach half way around the globe,

and poured resources

into china's infrastructure,

making its grand canal the

longest anywhere in the world.

With dadu, he'd laid the

foundations for what is today,

one of the greatest

cities on earth.

And it all started with

the wonder of xanadu.

I came here wondering

if marco polo was kind of

pulling our leg, you know,

exaggerating or maybe even

like that this was just

all the raving fantasy

of some mad italian.

And I'm satisfied what marco

polo was telling us was not

some kind of a myth, he was

really giving us a sense of

reality that he saw

with his own eyes.

Now, new technology is finally

revealing kublai khan's

astonishing city of xanadu.

Carefully planned and

beautifully constructed,

it was both mongol

and han chinese,

and on a magnificent scale.

Xanadu really was a

vibrant, cosmopolitan capital,

a cultural melting pot, filled

with amazing temples and

stunning palaces, fit for

an emperor who ruled over a

quarter of the

world's population,

and the biggest

empire on earth.

What we now know is that marco

polo was absolutely right,

xanadu was spectacular.