Over a hundred 'burial jars' and a dozen coffins arranged on a ledge in remote Cambodian jungle have for centuries held the bones -- and secrets -- of a mysterious people who lived alongside with the Angkor era.
Why the bones were placed in jars on a cliff some 100 metres (320 feet) high in the Cardamom Mountains, or indeed whose remains they are, has long puzzled experts.
For seven years Nancy Beavan, an archaeologist who specialises in carbon dating, has been looking for an answer, painstakingly piecing together clues left by the enigmatic people at 10 sites dotted across the area in southwestern Cambodia.
Tests show some of the bone fragments are six centuries old, according to the New Zealander.
"Why put these bones in jars? This was a practice that was not observed in any other part of Cambodia," she said.
Ten jars, dating from the 15th to the 17th centuries, and twelve coffins -- the earliest from the 14th century -- have been found at the Phnom Pel site.
Some are believed to have come from the kingdom of Siam, now Thailand.
Others, a minority, date back to the powerful kingdom of Angkor, which ruled for six centuries and built the famous Angkor Wat temple complex further to the north.
But experts remain mystified as to why the bones were preserved in a Buddhist country where cremation is -- and was -- a key religious custom.