♪ ♪ NARRATOR: Huge drawings etched into the Peruvian desert plains.

Birds.

A monkey.

And lines that stretch for miles.

♪ ♪ (Johny Isla speaking Spanish) (translated): They're one of the masterpieces of Andean society here in Peru.

NARRATOR: They are the Nazca Lines, remnants of a long-gone civilization that left its mark, quite literally, on the landscape.

(translated): Most of us in Peru descend from these populations.

NARRATOR: But the Nazca people are a mystery.

They had no written language, and the desert drawings they left behind had been baffling archaeologists for almost a century.

(Isla speaking Spanish) ISLA (translated): What function did they have?

It's a question we're still asking ourselves.

NARRATOR: Now researchers are using 21st-century technology to closely study the landscape.

♪ ♪ And they're discovering figures made before the Nazca were known to have existed.

Who lived here before the Nazca?

(translated): It's a mythological being-- look here.

Wow.

NARRATOR: Archaeologists are trying to piece together more than 1,000 years of history and have found evidence of thriving civilizations in Peru's southern desert.

(Giuseppe Orefici speaking Spanish) (translated): It is the largest adobe ceremonial center in the whole world.

NARRATOR: How did the Nazca Lines start?

What did they mean?

And why did they end?

♪ ♪ "Nazca Desert Mystery," right now, on "NOVA."

♪ ♪ (wind blowing) ♪ ♪ NARRATOR: It is one of the most arid deserts in the world, averaging less than an inch of rainfall a year.

And running along Peru's southern coast... ...more than 1,500 years ago, the people here created remarkable earthworks across an area spanning about 200 square miles.

Giant figures: a hummingbird.

A spider.

A monkey.

And thousands of lines, some more than five miles long, etched in the ground.

They are known as the Nazca Lines.

ISLA (translated): Technically, they are called geoglyphs, drawings on the earth.

(speaking Spanish) (translated): The Nazca geoglyphs can be seen in all their splendor from the air.

NARRATOR: Erosion and the remoteness of many of the lines meant that these vast designs were all but forgotten for more than a millennium.

♪ ♪ They were rediscovered in the 1920s, but it was not until airplanes started flying across the region that their true scale was revealed.

(Isla speaking Spanish) ISLA (translated): There are estimates about how many geoglyphs there are, around 6,000 or 7,000 geoglyphs.

Most, almost 90%, were geometric motifs-- lines, trapezoids-- and around ten percent figures.

NARRATOR: But what were they for?

And who created them?

Peruvian archaeologist Johny Isla has been studying the Nazca geoglyphs for more than 30 years.

ISLA (translated): The Nazca were a social group that developed along the southern coast.

This territory is pretty arid because there's no water for most of the year.

Their dwellings were along valleys, which are really small oases in the middle of the desert.

NARRATOR: Archaeologists named the ancient group of farmers and fishermen who once lived here the Nazca, after the local river valley.

♪ ♪ They used the surrounding desert plateaus as a canvas for drawing giant geoglyphs.

(Isla speaking Spanish) (translated): The Nazca covered these plains with geoglyphs and turned this desert into a space which was inhabited, dynamic, social, and vibrant through time.

(fire crackling) NARRATOR: Over the years, there have been many theories about these geoglyphs.

That they were astronomical calendars.

Signs left by aliens.

Or appeals to gods looking down from above.

But whatever the reason, the ancient people who lived in this area left a lasting mark in the desert.

♪ ♪ Today, urban expansion means some geoglyphs are on the outskirts of town.

MAN (translated): I live 500 meters from the geoglyphs.

Here in Nazca, we are proud of what the ancestors left us.

(woman speaking Spanish) (translated): Who knows what the ancestors were thinking when they did this?

But it's very beautiful.

NARRATOR: Nazca civilization disappeared more than a millennium ago.

But a growing interest in the past has spurred a revival of ancient Indigenous traditions, like the Yaku Raimi, a celebration of water.

CANDY HURTADO: The matter of indigeneity is very complex here in Peru.

People will not often identify as Indigenous.

It is still something that is associated with underdevelopment or a lack of progress.

But they will identify themselves through dances-- they will say, "I dance that, so I am that."

Um, "I sing that, so I am that."

(flutes and drums playing) NARRATOR: Candy Hurtado is an ethnomusicologist from Jauja in the highlands east of Lima.

She's studying rituals, and has come to Nazca to record the water festival.

HURTADO: In the Andean worldview, we understand that time is not linear, but that it is cyclical.

So that we are always, through ritual, connecting with the past, the present, and the future.

We're connected to our ancestors, we are connected to the people that come after us in a very real way, as well as to the environment.

The environment is also considered our ancestors.

♪ ♪ NARRATOR: Peruvian archaeologists studying the environment to piece together the Nazca story have made surprising discoveries.

Using drone images, they've identified a different type of geoglyph.

Not on the flat desert plateaus, but on the hillsides.

ISLA (speaking Spanish): NARRATOR: Johny Isla and his team are restoring his latest discovery, a very faded geoglyph.

ISLA (speaking Spanish): NARRATOR: Years of erosion have damaged the geoglyph.

Johny's team moves stone after stone by hand to re-expose the lighter layer below.

It's a painstaking process.

(speaking Spanish) (translated): When we realized that on the hillside there were other figures, other geoglyphs, we realized we have to change the way we thought and look to the hillsides, where we didn't think there were any drawings.

NARRATOR: The team has revealed the outline of a group of people walking, but it needs more work.

ISLA (speaking Spanish): NARRATOR: The desert hillsides have long been overlooked.

But now there is newfound interest in them.

ISLA (translated): It's really one of the most striking finds of recent times.

It's a mountain cat, the Pampas cat, an animal in danger of extinction.

NARRATOR: Almost 10,000 miles away, in Yamagata, Japan, archaeologist Masato Sakai studies drone footage from the Nazca desert.

He's turned to a high-tech method of searching for geoglyphs.

Artificial intelligence.

(speaking Japanese) SAKAI (translated): At the beginning, we were looking at the northern Nazca plains, where hummingbirds, monkeys, and other famous geoglyphs are concentrated.

(speaking Japanese) (translated): We let A.I.

learn from these famous geoglyphs and other data from this area.

NARRATOR: By analyzing aerial images, computer algorithms can spot the cleared surfaces that form the figures.

Once the A.I.

knows what to look for, it begins scanning the desert for patterns that appear human-made.

The software homes in on a very faint shape.

♪ ♪ (Sakai speaking Japanese) SAKAI (translated): We discovered it is a geoglyph of a person holding a club in their right hand.

NARRATOR: The person with the club, the people walking, and the Pampas cat were all found on the sides of hills.

And Johny thinks this unexpected positioning is the clue to their purpose.

(speaking Spanish) ISLA (translated): These geoglyphs were made by people for people.

As they're drawn on sides of hills, people could see them as they crossed the desert or the valleys.

(speaking Spanish) They seem to be markers of territory or routes through the desert.

NARRATOR: But it isn't only their position that is unusual.

They're in a different style from the classic Nazca images like the monkey and the hummingbird.

So were these giant geoglyphs made by the same people?

Or someone else?

To find out, researchers turn to other sources for designs and imagery that might match the figures on the hillsides.

(Isla speaking Spanish) ISLA (translated): To identify and categorize these geoglyphs, we take a stylistic approach.

We compare them with ceramics and textiles.

♪ ♪ NARRATOR: They find similar motifs, but not from the Nazca period.

ISLA (translated): These geoglyphs date to the year 200 or 300 BCE, which means that they were made before the famous Nazca geoglyphs.

NARRATOR: The hillside geoglyphs were created earlier than the Nazca are thought to have existed.

So who was making geoglyphs before the Nazca-- and why?

♪ ♪ In the 1920s, Julio César Tello, the first Peruvian archaeologist, found 429 mummies wrapped in extraordinary textiles in an ancient burial ground in the Paracas Peninsula.

So archaeologists called the ancient people the Paracas.

The funerary bundles are stored in Lima, in the National Museum of Archaeology, Anthropology, and History of Peru.

♪ ♪ The fabrics the mummies were wrapped in reveal the extraordinary skill and artistry of the Paracas.

And the images and symbols provide insight into their worldview.

There are shamans in trances.

Deities.

And severed heads.

One of the most iconic Paracas textiles has only recently arrived at the museum.

DELIA APONTE (speaking Spanish): APONTE (translated): In the 1930s, after Julio Tello's excavations in the Paracas Peninsula, there was a lot of looting, and some pieces, this one among them, were taken out of the country.

It ended up in Sweden.

NARRATOR: This is the first time archaeologist Delia Aponte has been able to examine the 2,000-year-old mantle.

(speaking Spanish) (translated): I'm happy.

I've always wanted to see this piece.

I'm surprised by the use of color.

For the Paracas, colors have meaning, and the way they organize them is important.

It's part of their identity.

There is a symbolism we haven't deciphered yet, but which is definitely there.

NARRATOR: The Paracas imbued their funerary textiles with meaning, and Delia is particularly interested in their symbolism.

(Aponte speaking Spanish) APONTE (translated): Here we have a toad, associated with humidity and agriculture.

A few plants are sprouting from its back.

(speaking Spanish) (translated): Here there is a condor.

Hummingbirds drinking from a flower.

A bean in the form of a human.

NARRATOR: The imagery related to animals and edible plants throughout the seasons suggests that the Paracas textile is a symbolic representation of the agricultural cycle.

(translated): I think this is a masterpiece, the pinnacle of 900 years of this society's development.

NARRATOR: Many of the Paracas images strong resemble the newly identified hillside geoglyphs found in the Nazca region.

It suggests the desert figures were created by the Paracas.

♪ ♪ The Paracas were ancient Peru's most accomplished weavers.

Today, communities in the highlands of Cusco keep some of their ancient traditions alive.

(Nilda Callañaupa Alvarez speaking Spanish) (women talking softly) ALVAREZ: Over here, they are warping, which is also traditional technique from the Paracas culture.

NARRATOR: Nilda Callañaupa Alvarez is a weaver and expert in textiles from Chinchero in the Cusco region, 350 miles from Lima.

She has made it her mission to preserve and promote pre-Hispanic weaving methods.

And here, in Pitumarca, she works with weavers who practice Paracas weaving techniques.

(all talking softly) Paracas have managed many techniques which they adorned the huge mantles for afterlife.

Textile tradition, practiced today, part of the traditional clothing and part of our identity.

So different regions will have different types of textile.

We are very lucky to have ancestors, civilizations, cultures like Paracas who left to us such rich textile tradition.

We, as weavers today, we like to learn those techniques, and we like to reintroduce, pass to the younger generation for the future.

NARRATOR: Paracas finds were not limited to the peninsula.

Archaeological discoveries reveal the civilization stretched across a swath of land almost 250 miles north to south.

And there is evidence of a settlement at a site called Animas Altas, Animas Bajas.

(Aïcha Bachir Bacha speaking French) (translated): I can see that this figure was cut at the neck.

It could be the sacrifice of a figure which could actually represent a human sacrifice.

NARRATOR: Archaeologist Aïcha Bachir Bacha has been piecing together the history of this 250-acre site.

(Bacha speaking French) (translated): Since 2009, we've discovered the façades of pyramids and also tombs of members of the elite.

(speaking French) (translated): And we also discovered low platforms which were workshops and residential sites.

NARRATOR: At the end of the dig season, the excavated areas get filled in to protect them, but Aïcha can use the data the team collected to reconstruct the ancient Paracas site.

(Bacha speaking French) BACHA (translated): The 3-D reconstructions of the buildings at Animas Altas, Animas Bajas help us to show that under all that sand, we really have an Andean town which developed 2,500 years ago.

NARRATOR: This settlement appears to have been abandoned around the year 100, when the site was covered in earth and buried by the Paracas, creating earthen mounds known by the Quechua name of huaca: something sacred and revered.

♪ ♪ The finds at Aïcha's site reveal objects and practices similar to other Paracas locations.

Some 75 miles to the north, in the Chincha Valley, lie more Paracas sites: 20 massive huacas overlooking today's farmland.

HENRY TANTALEÁN: Wow.

(Charles Stanish speaking Spanish) TANTALEÁN: Wow.

NARRATOR: Archaeologists Charles Stanish and Henry Tantaleán have worked here for more than a decade.

TANTALEÁN: Classical Paracas.

NARRATOR: Some of the huacas now have buildings or entire villages built on top of them.

But Charles and Henry's team have been excavating some of the mounds, such as this one, called Huaca Soto.

STANISH: You can see a giant sunken court here, so we assume that this would have been painted in beautiful colors, at least white and red, probably yellow.

We found stairs on either side of these courts.

We discovered a spondylus shell and various other evidence of feasting.

NARRATOR: Spondylus shells, the remains of shellfish brought from as far away as Ecuador, were considered prestige offerings associated with water and fertility.

Charles and Henry believe that it means this, Huaca Soto, was a Paracas ceremonial site.

♪ ♪ Adobe walls erode over time, so it's difficult to be sure exactly what Huaca Soto looked like, but it was clearly a monumental structure.

STANISH: For many years, we thought that these were only ritual centers, but now we realize, after our excavations down below, that there's at least a square kilometer of village adjacent to the pyramids.

We had a huge population living down there.

NARRATOR: Charles and Henry realized that the huacas were right in the middle of a densely populated landscape.

STANISH: We have buried villages, there's a massive settlement system, a number of political centers, a ritual center, and this was the demographic, political, and cultural capital of Paracas.

♪ ♪ NARRATOR: Several miles away in the desert, Charles and Henry found a network of five more huacas.

Archaeological finds suggest these remote platform mounds were also religious centers.

TANTALEÁN (translated): People used to get together here to do celebrations.

Over here, we found a group of six mummies from the Paracas era-- they were women.

We also found the remains relating to elites, who were possibly directing the worship that took place in this pyramid.

NARRATOR: As well as looking at the huacas, the archaeologists studied the surrounding desert.

And made a startling discovery.

STANISH: As you can see behind, there's a long line, a couple kilometers long, that goes all the way to right in the middle of the Paracas site.

NARRATOR: It's one of several lines that lead straight to the desert mounds.

But that's not all.

So we can see up ahead a large pile of rocks.

It's an intentional mound that is integrated into all of the lines, and this was one of the many many places, about 200, that we found throughout the entire geoglyph area.

NARRATOR: Charles believes these were altars where Paracas pilgrims might have left offerings.

STANISH: If you use the analogy of pilgrimages from around the world, from almost all cultures-- Hindu, Christianity, Muslim-- they all have these kinds of pilgrimages where people stop, and they know exactly what's to be done and when it's to be done, and this is exactly what we see throughout all of these lines.

♪ ♪ NARRATOR: Charles and Henry think that these altars were ritual stops on the lines which led people to their ultimate destination: the desert ceremonial centers.

But what motivated people to go on this journey?

(translated): In the Andes, a classic way of joining spaces together and of survival is by exchanging goods from different ecological zones.

So people from the coast gave fish, and those from the mountains crops, for example.

NARRATOR: But the finds at the desert huacas raise a question: with the Paracas capital in the lush green valley just a few miles away, why would the Paracas choose to meet and trade in the desert?

The archaeologists have a theory.

STANISH: The reason they chose this landscape is because it was barren, it wasn't owned by anybody, and it was neutral.

Paracas had a lot of intra-ethnic fighting going on: trophy head-taking and all this and that.

And so we know from history and ethnography that people will set up these neutral spaces, in-between zones, where both, all parties feel comfortable.

And here you can feel quite comfortable.

NARRATOR: Charles and Henry believe that the desert was the setting for periodic markets where goods were exchanged.

♪ ♪ And the orientation of the lines and mountains suggest the Paracas markets may have been held during the Winter Solstice, which in Peru takes place in June.

STANISH: One of the great theories as to why civilization developed is that people in pre-capitalist times developed these elaborate marketplaces, fairs, pilgrimage areas, where the people came together and they exchanged products, and marriage partners, and gossip, and have a good time, and this is how civilization really gets a kickstart.

♪ ♪ NARRATOR: The last Paracas offerings and sacrifices at this site were made around 250 BCE, before the ceremonial center was covered with earth and abandoned.

♪ ♪ So what happened to the Paracas?

Bioarchaeologist and forensic anthropologist Elsa Tomasto-Cagigao looked to DNA for an answer and got a surprise.

TOMASTO-CAGIGAO (translated): There is a DNA type which is specifically inherited from the mother and is very easy to classify.

In Native American populations, there are only four lineages-- A, B, C, D. And when I did a test for research purposes, it turned out I matched the D lineage most common among the Paracas.

NARRATOR: DNA analysis of human remains dating from 800 BCE to the year 800 helps explain what became of the Paracas.

(translated): In the Palpa and Nazca area, it's very difficult to differentiate biologically between the Paracas and the Nazca; they are genetically very similar.

Yes, we find cultural differences, which makes sense.

As the centuries go by, people change in the way they behave.

♪ ♪ NARRATOR: The research suggests that sometime before the year 100, the culture of the people living in the region shifted and the Paracas became the Nazca.

And while the styles changed, the Nazca continued the Paracas line-making traditions.

♪ ♪ But there were other similarities, too.

As archaeologist Giuseppe Orefici found when he arrived in this area 40 years ago.

(Orefici speaking Spanish) (translated): When we got here, we found a hill which had the remains of walls and a surface.

(speaking Spanish) It was a clue that there was something there, not just a natural hill.

♪ ♪ NARRATOR: The site, called Cahuachi, turned out to be a huge Nazca complex.

(Orefici speaking Spanish) OREFICI (translated): It is the largest adobe ceremonial center in the whole world, 24 square kilometers of great pyramids, large ceremonial enclosures.

There was a lot going on with pilgrims arriving from almost 1,000 kilometers away.

Cahuachi was the center, the beating heart of Nazca civilization.

♪ ♪ NARRATOR: But there were no signs of permanent settlements.

So although similar to the older Paracas sites of Chincha, Cahuachi was a different type of ceremonial center.

OREFICI (translated): It was a pilgrimage site where people cannot access all areas.

They have places they are allowed in, and where they can perform their rituals.

NARRATOR: Giuseppe believes that priests performed their own rituals inside the pyramids, while the pilgrims remained camped outside.

OREFICI (translated): We excavated a few temporary campsites people went to.

They ate the food they had brought, and they could see from a distance what was happening inside Cahuachi.

♪ ♪ NARRATOR: Just outside Cahuachi, a team of researchers has made a discovery.

NICOLA MASINI (speaking Italian): ROSA LASAPONARA (in Italian): ♪ ♪ (shutter clicks) LASAPONARA: MASINI: LASAPONARA: ♪ ♪ (translated): We do archaeology without digging.

A non-invasive archaeology.

We do this with satellite remote sensing, remote-sensing planes, drones, and also with geophysical exploration techniques.

NARRATOR: Nicola Masini and his team have found lines leading to the Nazca ceremonial site.

(Masini speaking Italian) MASINI (translated): We can see a clear spatial and functional relationship between the geoglyphs and the pyramids.

(drone whirring in distance) ♪ ♪ NARRATOR: They found evidence that the pilgrims outside the Nazca ceremonial center were more than just spectators in the events.

(translated): In this area, the entire setting of the geoglyphs is mainly made up of meandering elements, which clearly evokes the ritual activity of the processions.

Imagine the Nazca praying, singing.

♪ ♪ NARRATOR: So Nicola believes that while the Nazca religious elite could perform in the pyramids, the pilgrims carried out their own ceremonies along or within the lines in the desert.

♪ ♪ MASINI (translated): The geoglyphs and the pyramids can be seen as two faces of the same coin, of ceremonial activity which took place inside those structures, in the rooms and corridors of the pyramids.

But ceremonial activity also took place along these geometric shapes.

♪ ♪ NARRATOR: At the height of the Nazca civilization, sometime before the year 400, the evidence suggests different lines were created for different purposes.

Straight lines led to ceremonial centers.

Meandering ones were a stage for ritual.

And the famous images were also used for rituals, and perhaps to appeal to the gods.

But barely 300 years later, Nazca line-making fades away to nothing-- why?

(translated): Some figurative motifs drawn in the pampa were erased or deliberately covered up by the Nazca themselves.

NARRATOR: Before line-making dies out, the Nazca draw new shapes over some of their earlier figurative geoglyphs, and large geometrical shapes such as trapezoids become more common.

♪ ♪ Finds within these new geoglyphs hint at them no longer being simply pathways for processions.

The Nazca were using them differently.

(translated): We're at the base of a trapezoid made of stones, and the borders are well laid out.

They finish at a more narrow point where there are two small platforms, where we think rituals took place.

♪ ♪ NARRATOR: Johny believes that the shift in design means there was a widespread change in the Nazca rituals.

And there was a new element to the geoglyphs.

(Isla speaking Spanish) ISLA (translated): We identified small mounds or altars in the desert, altars with a series of things the ancient people left offerings.

Like things they grew in the valleys, seashells from the ocean, objects made of copper or semiprecious stones, and spondylus shells.

♪ ♪ NARRATOR: These altars were no longer ritual stops along the way, as they had been in Paracas times.

For the Nazca, they were a focal point of worship on the trapezoids, playing a much more central role.

♪ ♪ What happened to cause such a change from the Nazca's previous geoglyph-making tradition?

♪ ♪ In Cahuachi, Giuseppe found some clues.

(translated): This is a big ceremonial precinct, one of the places where ceremonies were held.

When we excavated it, it was completely covered by a layer of alluvial soils.

NARRATOR: Alluvial soils are deposited by surface water.

They're evidence of flooding.

OREFICI (translated): We found a boy in it who had been carried here by the water who had drowned.

NARRATOR: There is evidence that the area had been hit by a major flood, and the layers of sediment here reveal this flooding wasn't an isolated incident.

It was a recurring event.

OREFICI (translated): There are frequent floods, one after the other, as well as a terrible earthquake, which destroys a large part of Cahuachi.

NARRATOR: Today, the region experiences flooding at two- to seven-year intervals, caused by the weather phenomenon known as El Niño.

A warming of Pacific seawater leads to low air pressure, increased rainfall, and flash flooding.

It was a mega El Niño event followed by an earthquake which destroyed large parts of the ceremonial center of Cahuachi sometime around the year 400.

Giuseppe found thousands of shards at Cahuachi, remains of valuable pottery, which was smashed at the pyramids, most likely as a sacrifice as the Nazca appealed to the gods.

♪ ♪ (translated): There was a big change in Nazca society and its relationship with the deities.

It seemed the gods had abandoned them.

♪ ♪ NARRATOR: And Giuseppe believes that, in response, the Nazca abandoned Cahuachi.

♪ ♪ The floods were followed by periods of prolonged drought.

And the layout of big trapezoids hints at the Nazca's main concern.

ISLA (translated): Many point towards the most important mountains in the region, which is where the water comes from in the summer months.

♪ ♪ NARRATOR: In Las Trancas, one of the region's valleys, Nicola Masini and his team think they may have found an answer to how the Nazca dealt with their increasingly serious water problem.

MASINI (translated): From satellite images, we discovered these peculiar round shapes.

♪ ♪ NARRATOR: Near the round mounds, they come across something else.

LASAPONARA (speaking Italian): MASINI: LASAPONARA: MASINI: LASAPONARA: ♪ ♪ NARRATOR: They find a trapezoid geoglyph close to these mounds.

It points to Cerro Marcha, the mountain that provides the region with water in the summer months.

It suggests the mounds are significant for something.

(translated): Today we will do a 3-D study with the drone.

And then we'll go over with georadar, a geophysics research tool.

NARRATOR: The drone and ground-penetrating radar find evidence of an underground tunnel, the remains of an ancient aqueduct called a puquio.

♪ ♪ The Nazca engineered an extensive network of aqueducts, which tapped into subterranean water coming from the mountains, allowing them to bring it to the surface to store and distribute.

♪ ♪ (translated): So we have four elements of the landscape: the sacred mountain; the geoglyph, where the ceremonial and ritual activity takes place; the puquio, seen for its ability to produce water almost as some sort of miracle, which is why they thanked the deity.

And the result of all of this is the valley, an oasis where they farmed.

NARRATOR: There may have been as many as 50 aqueducts in Nazca times.

36 are still in use today.

♪ ♪ The rise of the trapezoid geoglyphs coincides with an increase in dramatic and violent images on Nazca pottery around the year 500, including trophy heads in greater numbers than before.

♪ ♪ Are things getting desperate for the Nazca?

(Tomasto-Cagigao speaking Spanish) (translated): Trophy head iconography is very common among the Nazca, and real trophy heads have been found.

It could have been confrontations between different communities, between enemies.

But another theory is that it could be a ritual.

(crowd shouting) NARRATOR: Elsa believes the Nazca may have appealed to their deities in a way similar to an ancient and violent ritual still practiced today.

(crowd shouting) TOMASTO-CAGIGAO (translated): Today, in the Cusco region, in Canas, a ritual war is waged among communities that are not enemies, and who, on a given date, in a given space, come together in confrontation.

It's a real confrontation.

People die and are injured, and the blood that is spilled from these clashes is seen as an offering to the Mother Earth relating to fertility.

(crowd shouting) NARRATOR: Could the Nazca have practiced bloody rituals as a response to a lack of rainfall?

♪ ♪ What was causing the droughts?

Were they just part of natural climate cycles, or was something else going on?

♪ ♪ More than 6,000 miles away, at Britain's Royal Botanic Gardens, Kew... ...conservation botanist Oliver Whaley and archaeobotanist David Beresford-Jones have been trying to understand the environmental and ecological pressures the Nazca were facing.

About 20 years ago, they were studying changes in the ecosystem.

Traveling off-road through the desert, they found one environment they didn't expect.

We came across a dune, and we found a twittering, uh, warm and green, verdant forest, almost sunken into the desert.

♪ ♪ NARRATOR: The Usaca forest is six miles long and only a few miles from the Nazca ceremonial center at Cahuachi.

It was full of absolutely enormous trees, a very cool, shady, beautiful forested environment.

And it suddenly made me think that perhaps the environments of the past were rather different to the sorts of environments one sees today.

NARRATOR: In order to test his hypothesis, David and his team analyzed soil from different areas in the Nazca desert.

BERESFORD-JONES: We took samples from the floor of the Usaca woodland, and then we compared those to soil samples from parts of the south coast which are today desertified.

And we found that the pollen samples were directly equivalent.

In other words, these now desert landscapes had once been forested.

(insects chittering, birds twittering) NARRATOR: What happened to the forests?

The soil samples show trees in the earlier layers were later replaced by agricultural crops.

The forests had been cut down by the Nazca.

But why?

After the year 500, a rising empire from the Andean highlands, the Wari, was spreading out across Peru.

Distinctive Wari finds show they reached the Nazca region.

BERESFORD-JONES: One of the reasons Wari were on the south coast was because they wanted to extract cotton, which they couldn't grow in the highlands.

NARRATOR: The Nazca valleys, kept fertile by the aqueducts, were perfectly places to grow cotton and other crops.

Coming under the influence of a more powerful civilization, the Nazca cut down their forest to make space for agriculture.

WHALEY: The Nazca were pushed by the Wari to overextend their agriculture, eating into the last relics of, of forest.

NARRATOR: David and Oliver tried to gauge just how much of the Nazca's forests still exist.

We estimate that from the original early Nazca forest extent, we've probably got less than five percent.

It's probably two or three percent of the original forest cover.

♪ ♪ NARRATOR: For centuries, the trees had maintained an ecological balance.

And large-scale deforestation led to a tipping point, causing irreversible damage to the ecosystem.

The ground became vulnerable to erosion, and the lack of trees sped up desertification.

For the Nazca, it marked the beginning of the end.

WHALEY: So this is what the forest was like in 2001.

NARRATOR: Today, what little remains of the ancient Nazca woodland is under threat once again.

It is being cut down and burnt to be sold as charcoal.

Tragic.

Yeah.

♪ ♪ NARRATOR: To try and stop the illegal deforestation, Royal Botanic Gardens, Kew supports scientists and conservationists who monitor the remaining Usaca forest.

Alfonso Orellana Garcia is local to the area.

♪ ♪ GARCIA (translated): This is a huarango tree forest.

The mother tree, the tree of life, that's what we call the huarango.

By burning, felling our trees and making forests disappear, we are repeating past mistakes.

♪ ♪ NARRATOR: Today, Usaca is a dwindling haven for wildlife familiar to the Nazca, like hummingbirds.

♪ ♪ And the Pampas cat, etched into the hillside.

♪ ♪ Geoglyph-making, which began with the Paracas but reached its peak in Nazca times, starts declining as Nazca society falls apart.

♪ ♪ ISLA (translated): This tradition of making geoglyphs ended around the year 650, 700, when Nazca society in this region also came to an end.

NARRATOR: The evidence suggests that as they faced ecological collapse, many Nazca abandoned this landscape and scattered, assimilating into the Wari.

TOMASTO-CAGIGAO (translated): They had to emigrate.

Some went eastwards, up the mountains, where the rains were more frequent.

Others went south.

♪ ♪ NARRATOR: The remnants of the great civilizations of the Paracas and the Nazca remained etched into the landscape, virtually forgotten for hundreds of years.

Today, archaeologists believe that the geoglyphs were multifunctional.

They were ritual pathways, territorial markers, the stage for ceremonies.

♪ ♪ Their design and use changing over a millennium.

♪ ♪ And the legacy of the sophisticated societies that created the lines lives on.

♪ ♪ (translated): The descendants of the Paracas, of the Nazca, of the Incas, we are alive, we are here.

Most of us in Peru descend from these ancient populations.

And we are very proud of our Indigenous past, and interested in learning about it, and we cherish it.

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Or call 1-800-PLAY-PBS.

Episodes of "NOVA" are available with Passport.

"NOVA" is also available on Amazon Prime Video.

♪ ♪ ♪ ♪