For more than a century, a sprawling city of the Khmer Empire known as Mahendraparvata, dating from the 8th to 9th century CE, has both intrigued and mystified archaeologists. Now, novel technologies are allowing researchers to map the region in great detail for the first time, not only confirming its location but adding to the mystery that makes up this ancient urban metropolis.
The Khmer Empire reigned what is now Cambodia between the 9th and 15th centuries and is best known for Angkor Wat, a vast temple complex. Mahendraparvata predates Angkor and could be the first large-scale city planned and built according to a grid system.
Until now, archaeological evidence was limited to small and isolated shrines scattered throughout the countryside of Phnom Kulen plateau. Structures built by the Khmer Empire were primarily made of wood and other perishable materials that have since disappeared. But archaeologists can trace structural contours of the terrain, which leave a “durable legacy” on the surface of the Earth.
But dense vegetation and unexploded land mines from civil unrest during the 1990s make ground surveys difficult. Using airborne laser scanning (LiDAR), a revolutionary technology that can see through vegetation and provide high-resolution models of the forest floor, archaeologists for the first time have extensively mapped Mahendraparvata. LiDAR technology has been previously used to discover thousands of ancient Mayan structures and a mega-city in Guatemala. When combined with the ground-based survey, the findings allowed archaeologists to determine the boundaries of the ancient city of Mahendraparvata dating back more than 1,200 years.
Between 2012 and 2017, archaeologists visited 598 newly documented features. When combined with LiDAR technology, the work resulted in the discovery of thousands of archaeological features, stretching across an area of 50 square kilometers (20 square miles) around a centrally planned urban area. A “framework of linear axes, oriented roughly to cardinal directions” was found that connected dams, temples, neighborhoods, and the royal palace, wrote researchers in the October issue of Antiquity. Their work may have even discovered city blocks that align in a grid-like pattern similar to modern cities suggesting it was built with a city plan in mind.
Unfinished man-made lakes were also found, suggesting that the water management system may not have been able to support rice agriculture. Radiocarbon dating of mysterious mounds scattered throughout the region suggests they date back to around a millennium ago. It is unclear what they were used for though the researchers have ruled out funerary practices or habitation.
“The work described here effectively draws to a close 150 years of archaeological mapping work in the Greater Angkor region and sets the stage for more sophisticated spatio-temporal modeling of urban form,” write the authors, adding that this work is “crucial for understanding the historical trajectory of Angkor and the Khmer Empire.”