Ancient Urban Sprawl Surrounded Angkor Wat

The famous medieval temple at Angkor Wat in Cambodia was once surrounded by a giant urban sprawl of settlements, according to a new map of the area published by an international team of archaeologists. The experts spent years studying Nasa images of the Angkor region and checking possible sightings on the ground, and found enough ruins to conclude that the site was the largest settlement in the pre-industrial world.

Carpeted with vegetation and obscured by low-lying cloud, the ruins spill over 400 square miles around the distinctive temple, and are linked by a complex irrigation system.

The findings could pose a problem for conservation experts, as the historical remains spread beyond the designated World Heritage site around the temple.

Damian Evans of the archaeological computing laboratory at the University of Sydney, and colleagues from Australia, Cambodia, and France combined information from hand-drawn maps, ground surveys, airborne photography and radar provided by Nasa. The radar can sense differences in plant growth and moisture content produced by small changes in surface structure or height. The team found evidence of more than 1,000 new man-made ponds and at least 74 ruined temples. One hydraulic system linked the network and was probably used to provide citizens with a stable water supply. They also discovered two mysterious giant earthen structures.

The new map was published last night in the journal Proceedings of the National Academy of Sciences.

The experts said: "Even on a conservative estimate, greater Angkor at its peak was the world's most extensive pre-industrial low-density urban complex."

The city stood from the ninth to the 16th centuries. The team said there were signs its citizens engineered their downfall by disrupting the environment.

"Angkor stands in a vast expanse of rice fields that would have required extensive forest clearance over the entire Angkor plain and up to the Kulen and Khror hills to the north," the experts said. "The new maps show that land use modification at Angkor was both extensive and substantial enough to have produced a number of ecological problems, including deforestation, overpopulation and erosion."