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Public domain. The temple of Angkor Wat in Cambodia.

Ancient Cities Were Swallowed by the Cambodian Rainforest

Archaeologists uncover massive metropolises, forgotten by time.

| 2 min read

Archaeologists uncover massive metropolises, forgotten by time.

Archaeologists working in Cambodia have revealed the remarkable complexity of ancient medieval cities that have since been reclaimed by the rainforest.

As part of the Cambodian Archaeological Lidar Initiative (CALI Lidar), researchers identified a surprisingly complex hydraulics system, quarries, and other features that may overturn established timelines of Cambodia’s history.

The findings make use of Lidar, a technology based on the same principles as radar that uses light instead of sound to measure distance. Pulses of light are emitted from a helicopter flying over the site and the time it takes each pulse to hit the ground and return to the helicopter lets archaeologists reconstruct the footprints of cities that would be obscured by trees in other survey techniques.

A 2012 survey using these methods uncovered the city surrounding the temple of Angkor Wat, which revealed impressive dams and waterways, constructed centuries before historians believed the technology had been developed. A second survey in 2015 examined an additional 2000 square kilometers including four more cities from the Khmer empire. Detailed results of this initiative will be released in the coming weeks, starting with a peer-reviewed article in the Journal of Archaeological Science.

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One of the sites described in the new results is Preah Khan of Kompong Svay, a city built between the 10th century and the late 12th century. Lidar revealed Preah Khan to have the same basic arrangement as Angkor, with a temple in the center surrounded by a walled city.

Topographic relief of Preah Khan of Kompong Svay.

Topographic relief of Preah Khan of Kompong Svay. Credit: Cambodian Archaeological Lidar Initiative

The city itself was divided by moats and waterways into blocks measuring approximately 120 by 120 meters. The site had been extensively looted in the 1980s and 90s, but the lidar data enable archaeologists to identify one block that was largely untouched by looters.

Excavations on the ground verified the presence of an ancient settlement and religious buildings in Preah Khan of Kompong Svay, which had been a major industrial center for the Khmer Empire. Archaeologists found ceramics, charred animal remains, and three Chinese coins, which were likely destined to be melted down for their metal rather than used as currency.

The CALI Lidar team will continue to undertake field investigations at Preah Khan and the other surveyed sites until 2020.

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