Mysterious Earthen Mounds Found At Angkor Wat: Vast Ancient City Networks Revealed By Lasers

In the jungles of Cambodia surrounding the intricately beautiful Angkor Wat, scientists have discovered an extensive network of huge medieval cities stretching out and away from the ancient temple. These networks have remained hidden for hundreds of years, forgotten by the world. But archaeologists using special laser equipment have uncovered evidence of cities around the Angkor Wat area that are far larger than had been previously thought, and within the cities lies a mysterious gridwork pattern of earthen mounds.

Live Science reported June 14 that archaeologists, who have been working the area for years, discovered numbers of earthen mounds arranged in geometric shapes (even spirals) in the multiple medieval cities hidden in the jungles of Cambodia that have been found and unearthed around the vast tourist attraction Angkor Wat since the 1990s. Scientists, using laser scanning equipment to penetrate the jungle, have been working with data taken in 2015 that encompassed over 735 square miles. That data revealed the 1,000-year-old cities that scientists have long thought existed around the important temple complex of Angkor Wat.

Australian archaeologist Damian Evans of the École française d'Extrême-Orient told Agence France-Presse, "We always imagined that their great cities surrounded the monuments in antiquity."

To get the data, Evans and his colleagues mounted special laser equipment, called lidar (an acronym for Light Detection And Ranging), to penetrate and peer through the thick Cambodian jungle canopy. Evans noted that much of the structures of the cities were made of wood and thatch -- unlike the stone used to construct Angkor Wat -- and had rotted away over the years.

"The lidar quite suddenly revealed an entire cityscape there with astonishing complexity," Evans said. "It turned out we'd been walking and flying right over the top of this stuff for ten years and not even noticing it because of the vegetation."

Angkor Wat is a UNESCO World Heritage site and is considered one of the seven wonders of the ancient world. It was constructed in the mid 1100s by King Suryavarman II, who ruled at the height of the Khmer Empire, which was believed to have been in decline by the 15th century. The city was believed overrun by Thai invaders, and the people were supposedly forced to become refugees and relocate to the south, but Evans and his team found no evidence to support a dispossessed population and the lidar found no southern cities to support the presence of a mass migration.

The temple complex of Angkor Wat was part of one of the largest pre-industrial cities in the world. And now archaeologists know that its metro area was much larger. In fact, Evans and company found evidence of a cityscape as far as 20 miles outside the temple area.

In Evans' words (per The Guardian), "... the size of Phnom Penh big." The modern capital of Cambodia, Phnom Penh covers nearly 265 square miles of territory.

As for the newly discovered earthen mounds (or "dome fields," as they are referred to), their purpose is as yet unknown. "Surface surveys and excavations of these mounds have revealed little of archaeological interest, and they remain among the most enigmatic features of Khmer landscape archaeology," Evans wrote in a paper on the discovery published by the Journal of Archaeological Science.

The archaeologist does not believe the mounds will be much of a tourist draw. Just as mysterious, he wrote in the study, were the "geometric rectilinear patterns made from earthen embankments and variously described as 'coils,' 'spirals,' 'geoglyphs' or 'gardens.'" The purpose for these patterns is also unknown.

The lidar data "clearly show an urban layout within the central moat of the site," Evans wrote. It is "surrounded by an extended, less-organized urban grid," he added.

Angkor Wat is one of the world's most visited tourist attractions. In 2015, Trip Advisor named the temple complex the top tourist site in the world. In 2014, Google added the city streets of Angkor to its "Street Views" feature, allowing a virtual tour of the ancient city and Angkor Wat for the first time.

[Image via Shutterstock]