Aerial view of the Phnom Kulen plateau and escarpment.
Image: Archaeology Development Foundation

Archaeologists in Cambodia have used jungle-penetrating laser to confirm the location and layout of an ancient capital city associated with the early stages of the Khmer Empire.

Researchers from the French Institute of Asian Studies and APSARA, Cambodia’s management authority for Angkor Archaeological Park, have used LIDAR to pinpoint the exact location of Mahendraparvata—an early Angkorian city and one of the first capital cities associated with the Khmer Empire. The ancient city, which dates back to the 8th and 9th century CE, was spotted in the dense jungles of Cambodia’s Phnom Kulen mountains. Details of the discovery were published today in the science journal Antiquity.

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The Khmer Empire dominated much of southeast Asia from the 9th to 15th century CE, establishing the foundations of modern Cambodia. Among its many achievements, the Khmer Empire is famous for Angkor Wat—an elaborate temple complex located in the ancient city of Angkor in northwest Cambodia. Mahendraparvata was built before Angkor, and it’s very possibly the first large-scale, centrally designed, grid-plan city built by the Khmer Empire, according to the new research.

Map showing the main grid lines of Mahendraparvata.
Image: J. Chevance et al., 2019/Antiquity

Inscriptions and other archaeological evidence had pointed to the Phnom Kulen mountain as the likely location of Mahendraparvata, but scientists were only able to uncover small and apparently isolated shrines. The city remained largely undetected owing to dense vegetation growing at the site, and because of the presence of Khmer Rouge guerillas who stayed in the area until the 1990s; the jungle remains littered with landmines and unexploded ordnance, making it an unsafe space for archaeologists.

To overcome these hurdles, Damian Evans, a co-author of the new study and a researcher at the French Institute of Asian Studies, conducted a LIDAR survey of the area in 2012. A second, more extensive survey was repeated in 2015. These laser scans produced high-resolution 3D maps of the forest floor pointing to the presence of previously undetected archaeological features, which were then explored and confirmed by archaeologists working on the ground.

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LIDAR map showing orientation of architectural features in Mahendraparvata and the reservoir.
Image: J. Chevance et al., 2019/Antiquity

The LIDAR scans revealed an urban area measuring approximately 40 to 50 square kilometers (15 to 19 square miles) in size, consisting of thousands of distinct archaeological features. Of significance, the 3D maps showed raised embankments arranged in north-south and east-west directions and squared city grids containing remnants of a once vibrant urban center. Within this central grid, the researchers uncovered small shrines, mounds, ponds, a royal palace, a pyramid temple, and “other infrastructural elements that are consistent with—and unique to—all other known Khmer Empire capitals,” the authors wrote in the study.

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Indeed, this was no ordinary urban center, as the researchers explained in the paper.

The existence of a palace precinct, a network of thoroughfares and local shrines and neighbourhoods indicate that a royal court was located here and supported by a substantial population of specialised ritual, administrative and other staff drawn from a broader community inhabiting an extensive, well-defined, built-up area. This area was clearly not rural in character, as it has no identifiable agricultural systems; furthermore, its extensive system of parcelled neighbourhoods indicate that it was not merely a vacant ceremonial centre.

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The dating of Mahendraparvata is still preliminary, but it appears to coincide with the time of Jayavarman II (770 to 835 CE), the first ruler of the Khmer Empire.

The researchers also found remnants of a large-scale water-management system that consisted of a dam and an unfinished artificial reservoir. Its unfinished condition meant the city was not able to support irrigated rice agriculture and that Mahendraparvata probably didn’t last long as the political center of the Khmer, according to the paper.

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Indeed, as a capital city, Mahendraparvata wasn’t meant to be, due to its mountainous location and lack of viable agricultural land. Angkor, the eventual capital of the Khmer Empire, proved to be a much better choice, mostly due to its rice-friendly floodplains. That said, the unfinished reservoir at Mahendraparvata could be seen as a precursor to the extensive reservoirs seen at Angkor hundreds of years later.

Annotated map of Mahendraparvata.
Image: J. Chevance et al., 2019/Antiquity

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“This would place the site among the first engineered landscapes of the era, offering key insights into the transition from the pre-Angkorian period, including innovations in urban planning, hydraulic engineering and sociopolitical organisation that would shape the course of the region’s history for the next 500 years,” wrote the authors.

Near Mahendraparvata, the researchers also found 366 individual mounds arranged in geometric patterns and built in groups of 15. The purpose of these mounds is unclear, but the lack of associated archaeological evidence suggests they weren’t funeral structures, former habitats, or architectural foundations. It will take further work to discern the purpose of these strange mounds as well as similar formations found elsewhere in Cambodia.

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