Mummies buried under a shanty town in Peru reveal secrets of the Incas' lost civilisation

More than 2,200 ancient mummified bodies have been found buried beneath a dusty shanty town on the outskirts of Lima, the capital of Peru, providing precious clues to the mysterious Incan civilisation.

More than 2,200 ancient mummified bodies have been found buried beneath a dusty shanty town on the outskirts of Lima, the capital of Peru, providing precious clues to the mysterious Incan civilisation.

The excavation of the cemetery, which has been kept secret for the past three years, has uncovered the greatest number of Incan mummies at a single site, complete with tens of thousands of buried artefacts.

It will take years to analyse the find but already the discovery is helping archaeologists understand more about one of the world's great "lost civilisations", which was destroyed by Spanish conquistadors in the 16th century.

Since work began at the Puruchuco site in 1999, the team of Peruvian and American scientists have dug out more than 1,200 "funerary bundles" where mummified bodies and possessions were carefully wrapped before being buried in pits four to five metres deep. One of the most stunning finds is the number of high-ranking burials called cabezas falsas, or "false-head" bundles, where a protuberance on top of the wrapping is filled with cotton to resemble a human head.

Since 1999 the archaeologists have excavated about 50 false-head bundles, some of which are adorned with a metal mask or a wig made of vegetable fibres dyed black. Only one false-head Incan funerary bundle had been discovered previously, in a 1956 dig.

Guillermo Cock, the Peruvian-born archaeologist who led the excavation, said the sheer number of burials and the presence of so many high-status mummies represented an unprecedented opportunity to solve some of the mysteries of the Inca before their empire was finally destroyed in 1572.

"The cabezas falsas are the largest bundles interred at the site. They always contain multiple individuals and include the finest artefacts both inside and outside of the bundle," he said.

"Although there are at least five types of false-head bundles, they share some characteristics: they contain more than one individual; they are buried within a group of bundles of different types and sizes, and they are buried in areas specially selected and prepared for the burial ceremony."

The archaeologists believe that most of the burials took place from around 1480 to 1535. Many of the mummies – about 45 per cent – were of children under 12, reflecting the high childhood mortality of the time.

Although mummification occurred naturally due to the bone-dry sandy soil of the area, it was actively encouraged as a way of preserving the dead, Dr Cock said. "It was natural but intentional. They wanted to preserve the bodies of their ancestors. The cult of the ancestor was very important," he said.

To encourage swift desiccation of the remains, each body was wrapped in several layers of either cotton, grass, leaves or wood chippings to absorb body fluids and halt the process of tissue decomposition.

Heather Pringle, author of The Mummy Congress, describes how important mummification was to the Inca, who had inherited their infatuation with ancestral worship from earlier, pre-Incan people living in the Andean mountains and the Atacama desert of Chile.

"In the Andes and Atacama desert, people did not see death as the end of life. Instead they believed it was just the beginning of a new and more influential phase as a revered ancestor who could lend assistance to the living," she writes.

Some of the most spectacular finds of the Inca have been mummies buried on the highest mountains, who had evidently been part of a sacrificial ritual. One of the most famous is the "Ice Maiden", the mummy of an adolescent girl dressed in fine garments and jewellery buried at an altitude of 20,000 feet on the Andean peak of Ampato.

Following the Spanish invasion of the Incan empire, many mummies were deliberately destroyed by the conquistadors, sometimes in public displays as a way of exerting power over the local population.

The Inquisition denounced the perfectly preserved mummies of the Incas as a devilish invention and urged the Spanish to destroy them, Ms Pringle said. "As such, the mummies had to be stamped out. And this had to be done with all the efficiency the new Spanish colonial authorities could muster, which was considerable."

In addition to the deliberate destruction, many Incan burial sites were also looted over the centuries and their precious mummies destroyed or damaged in the process. Dr Cock said that from early aerial photographs there are signs of some looting of the Puruchuco cemetery prior to the 1940s.

Nevertheless, many of the funerary bundles have escaped the attentions of the grave robbers. One, dubbed the "cotton king", is exceptionally well preserved. It is made of 300 pounds of raw cotton carefully wrapped around an Incan noble, a baby and about 70 items, including food, pottery, animal skins, and corn to make a fermented drink known as chicha.

Other bundles contain mummies still wearing the distinctive feathered head-dress that marked their rank in Incan society. Among the estimated 60,000 artefacts excavated from the site are delicate spondylus shells from Ecuador, which were used as adornments, and late-Incan ceramics of the Arybalo style.

Conditions at the site have been difficult, said Dr Cock. The archaeologists were not allowed to excavate underneath the shanty dwellings and so had to confine their digging to the streets and open spaces.

In addition, the lack of a sewage system meant that many burials were beginning to decompose for the first time in centuries as thousands of gallons of liquid waste were poured directly into the ground from the 1,240 families living in the shanty town above. "We were all afflicted with stomach problems, skin infections, colds and flu. I have had an infection in my throat since September 2001 that my doctors have not been able to kill," Dr Cock said.

"The destruction of the archaeological site was a big problem. After more than 10 years, with people living there, the amount of damage was tremendous. It really concerned us.

Last year the team received a second grant from the National Geographic Society in Washington DC to complete as much of the dig as possible. Only five of the 1,200 funerary bundles have so far been opened. They show that most of the mummies were buried in the traditional foetal position of the Inca but some were stretched out in the European style, perhaps indicating a cultural influence from the Spanish.

"We don't know whether this reflects the early influence of the Catholic Church or whether the Inca were just copying other forms of burial," Dr Cock said. Further work on each mummy will reveal details of age, sex, growth, nutrition, illnesses, possible causes of death and the genetic relationships.

It will take years before the full story of the Puruchuco cemetery can be told but the findings should make it possible to see the Inca in a new light. Dr Cock said: "This is a unique opportunity to study a period of time that is famous but yet about which little is known."

'Inca Mummies: Secrets of a Lost Empire' is screened on the National Geographic Channel on 19 May.