Perched in some cases on precarious cliff ledges, centuries-old log coffins—such as this one, pictured alongside researcher Nancy Beavan—and "body jars" are the only known traces of an unknown Cambodian tribe. Now new dating studies are beginning to assure the unnamed culture a place in history.
Ten such burial spots have been found in the Cardamom Mountains (map) since 2003, and at least one is at least 160 feet high (50 meters)—the intention apparently being that "anyone trying to disturb the burials would break their neck," said Beavan, who led the new study.
Beavan's team has radiocarbon-dated wood, teeth, and bones from four of the sites to between A.D. 1395 and 1650, placing them smack-dab in the decline of the Khmer Empire, based in Angkor. However it's unclear what, if any, influence the empire had on these mountain people, said Beavan, of the University of Otago's Department of Anatomy in New Zealand.
Until now, experts had no idea when the sites had been established or how long they'd been in use, she added.
Placing the sky-high burials couldn't have been easy, according to Beavan. Systems of ropes and bamboo baskets may have been used to raise or lower the urns and coffins to some of the trickier sites, she speculated.
Photograph courtesy John Miksic
Hewn from tree trunks some 700 years ago, several log coffins are pictured lined up like ramshackle piano keys beneath a rock overhang at the Phnom Pel burial site in Cambodia in 2010.
As well as being "a place apart spiritually," these "nearly inaccessible" burial locations may have been chosen to protect the dead, Beavan said.
Each of the Cambodian body jars (such as the one pictured here with bones at its bottom in 2010) had a hole drilled through its base, "perhaps to the ritually 'kill' the vessel"—to render it useless for any non-spiritual purpose, according to the new study.
The drilling "is part of the ritual of transforming that container, just as is breaking off the rim to allow emplacement of larger skeletal elements," Beavan said.
Human bones lie inside a log coffin at Phnom Pel—one of four newly dated burial sites that mark the remnants of a vanished culture from Cambodia.
The burials date to the last days of the Khmer Empire, which controlled large swaths of Southeast Asia from its Cambodian base at Angkor, more than a hundred miles (160 kilometers) away. (See pictures of Angkor from National Geographic magazine.)
However, the empire had little cultural impact on the mountainside grave-builders, the study team believes. For one thing, the people of Angkor followed the Hindu and Buddhist practice of cremation, Beavan said.
Photograph courtesy Nancy Beavan
Circles of Life
For the new dating study, wood samples were taken from only the outer—and therefore youngest—rings of the Cambodian log coffins, ensuring dates closer to when the tree had been felled. These and other clues are helping researchers slowly build a better picture of the people behind the perilous burials.
"These sites may be the only remaining evidence of this highland culture, and we may never be able to say for certain who these people were," Beavan said.
"But burial sites can tell researchers many things about a people, including health, demographics, and other hints about their lifeways."