‘Angkor did not suffer a sudden collapse’

Study says city’s decline was gradual

This picture taken on April 2, 2014 shows tourists visiting the Bayon temple, part of the Angkor architectural complex in north-western Cambodia. Cambodia's Angkor Wat has been digitally mapped for the first time, allowing people to visit the famed temples from the comfort of their armchair using Google Street View.

Angkor, the ancient capital of the Khmer empire, appears to have suffered a gradual decline rather than a catastrophic collapse, according to a study published on Monday.

Archaeologists and historians have long sought to explain the 15th-century abandonment of Angkor, with many attributing it to the 1431 invasion by Thai forces from Ayutthaya.

“The historical record is effectively blank for the 15th century at Angkor,” said Dan Penny, a member of a team of Australian and Cambodian archaeologists and geographers who took part in the study published in the

Proceedings of the National Academy of Sciences (PNAS).

Sediment cores tested

“We don’t have a written record that tells us why they left or when or how,” said Mr. Penny, of the School of Geosciences at the University of Sydney. “Everything that survived is carved on stone.”

For the study, the team examined 70-cm sediment cores taken from a moat that surrounded Angkor Thom, the capital of the Khmer empire.

Mr. Penny said the cores serve as a “natural history book recording changes in land use, and climate, and in vegetation, year after year.”

Where humans live, they leave traces through fire, soil erosion through agriculture and disturbed vegetation. When they leave, conditions change.

In the first decades of the 14th century, Mr. Penny said you start to see a decline in land use, wood burning, destabilised vegetation and a reduction in soil erosion.

By the end of the 14th century, “the southern moat of Angkor Thom was overgrown with vegetation, and management, by implication, had ceased,” the authors said in the study.