Before Angkor rose to prominence on the Cambodian plains, a city had already emerged as the center of Khmer power in the Phnom Kulen Mountains. That city was Mahendraparvata, the first capital of the Khmer Empire, established in the late 8th to early 9th century.
Located about 30 kilometers northeast of Angkor, the site is now regarded as one of the most important archaeological discoveries in Southeast Asian history. Its existence is recorded in ancient Khmer inscriptions, particularly the Sdok Kak Thom inscription, which directly links the city to the reign of King Jayavarman II.
Phnom Kulen, meaning “Mount Leech” in the Khmer language, was not merely a geographical setting. It was here that King Jayavarman II proclaimed independence from Javanese rule in 802 CE and inaugurated the Devaraja cult, which became the ideological foundation of Khmer royal authority.
Since 1992, the area has been included on UNESCO’s Tentative List as a potential World Heritage cultural site. Beyond its historical significance, Phnom Kulen also plays a crucial role as the headwaters of the Siem Reap River and other major rivers in the Angkor region, which later sustained the hydraulic systems of Angkorian cities and ultimately flow into Tonle Sap Lake.
A Planned City on a Mountain
Mahendraparvata was built on the Phnom Kulen plateau and covered an area of more than 40 square kilometers, about 70 kilometers south of the Dangrek Mountains and approximately 30 kilometers from Tonle Sap Lake.
Its location was highly strategic: the Siem Reap River and several other major waterways that irrigate the Angkor region originate here. Water from Phnom Kulen supported Angkor’s hydraulic system, including large reservoirs (baray), canals, and city moats.
The remains of this ancient city reveal a staggering scale. Within an area exceeding 40 square kilometers, archaeologists have identified around 40 brick temples, along with reservoirs, dams, canals, ponds, and earthen embankments that together formed a fully integrated urban system.
One of the most prominent structures is Prasat Rong Chen, a five-tiered stepped pyramid mountain temple built at the highest point of the southern Phnom Kulen plateau. In addition, archaeologists have identified a large, unfinished reservoir integrated into the city’s hydraulic network.
What makes Mahendraparvata exceptional is its urban layout. Unlike pre-Angkorian settlements that developed without clear planning, the city was organized according to a network of main axes laid out in a grid pattern.
These axes divided the central area into urban blocks, where temples, water features, and residential zones were arranged in a systematic manner. This makes Mahendraparvata the earliest large-scale experiment in grid-based urban planning in the Khmer world.
A City Reemerging from the Forest
For centuries, Mahendraparvata was all but forgotten, concealed beneath the dense forests of Phnom Kulen. A major breakthrough came with the use of LiDAR technology, which made it possible to map landscapes hidden beneath thick vegetation.
The results revealed networks of earthen embankments, urban axes, hundreds of ponds, and a large reservoir that was never completed.
The scans also confirmed the presence of a Royal Palace (banteay), which—together with the state temple Rong Chen and the main water infrastructure—firmly establishes Mahendraparvata as a royal capital during the reign of Jayavarman II.
These findings demonstrate that the city was not an empty ceremonial center, but a vast residential landscape with clearly defined neighborhoods and a substantial population.
Historically, Mahendraparvata marks a turning point in the development of Khmer urbanism. It served as a bridge between the relatively simple pre-Angkorian settlements and the far more complex Angkorian cities that followed.
This urban model was not immediately adopted by subsequent capitals. Hariharalaya, which became the center of power after Mahendraparvata, still displayed a more organic spatial layout. Only between the 10th and 12th centuries did monumental axial planning and urban grid systems reappear in Angkor on a large scale.
Living Legacy of The Sacred Mountain
Although it ceased to be a political center, Phnom Kulen never lost its sacred significance. After the royal court moved to Hariharalaya in the Roluos area, the region remained inhabited and ritually revered.
Archaeological evidence points to the continuity of religious activity: rock shelters occupied by hermits from the 10th century onward, carved riverbeds such as Kbal Spean and the Thousand Lingas, as well as prehistoric sites with rock art.
One of the most revered sites to this day is Preah Ang Thom, an eight-meter-long reclining Buddha carved between the 12th and 16th centuries. Phnom Kulen continues to function as a pilgrimage destination, where monks and modern hermits maintain the area’s spiritual continuity.
Phnom Kulen also played another crucial role, as the primary source of sandstone for the construction of Angkor. Ancient quarries at the foot of the mountain, fully mapped only through LiDAR surveys, reveal an industrial-scale operation that flourished from the 9th to the 12th centuries. It was from these quarries that the stones used to build the temples of Angkor were extracted.
