Phnom Kulen — whose name translates roughly to 'Mountain of the Lychee' — is considered the most sacred mountain in Cambodia, rising above the Cambodian plains north of Siem Reap in Siem Reap Province. The plateau is home to ancient sandstone carvings, a reclining Buddha hewn directly from the living rock, and the Kbal Spean river site where thousands of lingas are believed to have been carved into the riverbed to sanctify the waters flowing down toward Angkor. According to historical tradition, it was here in approximately 802 A.D. that the Khmer king Jayavarman II performed the devaraja ritual — declaring himself a god-king and effectively founding what would become the Khmer Empire — at a place scholars have long sought to identify as the lost city of Mahendraparvata. In Season 1 of Expedition Unknown, Gates travels to Phnom Kulen to investigate that founding moment, search for traces of Mahendraparvata, and examine the sacred linga ritual that may have given the mountain its spiritual power. The mountain is also a modern pilgrimage site for Cambodian Buddhists, who visit its waterfall and hilltop temples on weekends and religious holidays.
Jayavarman II reportedly conducts the devaraja ritual on Phnom Kulen, proclaiming himself god-king and founding the Khmer Empire, according to later inscriptions
The plateau is believed to have served as an early Khmer royal center, with lingas carved into the Kbal Spean riverbed and temples constructed across the mountain
Aerial LiDAR surveys reportedly reveal evidence of a large, previously unmapped ancient urban settlement on the Phnom Kulen plateau, fueling ongoing archaeological interest
Gates investigates Phnom Kulen in Expedition Unknown Season 1, Episode 2 — "Temple of Doom"
Phnom Kulen occupies a singular place in Khmer history and religion. According to inscriptions studied by epigraphers, Jayavarman II's devaraja ritual — conducted on or near the mountain around 802 A.D. — was the ceremonial act that unified fragmented Khmer polities under a single divine sovereign and broke the region's political ties to Java. The ritual involved a Brahmin priest establishing a cult of the sacred linga, the phallic symbol of the god Shiva, which would embody and legitimize royal power. Whether the site of that ceremony can be precisely identified remains an open question among specialists.
The broader mystery of Mahendraparvata — the 'Mountain of the Great Indra,' named in ancient inscriptions — drew fresh attention after aerial LiDAR surveys reportedly identified the outlines of a substantial ancient urban grid on the Phnom Kulen plateau, suggesting a planned settlement that predates or is contemporary with Angkor's early phase. Archaeologists working in the region have described the potential scale of the buried city as significant, though excavation and ground-truthing remain ongoing. No named experts appear in the available transcript evidence for this episode, so specific on-camera claims should be treated with appropriate caution.
The carved lingas at Kbal Spean, where the Siem Reap River flows over a bed of intricately cut sandstone, offer one of the most visually striking pieces of evidence for the mountain's sacred function. Water flowing over the lingas was believed to be ritually purified before descending to fertilize the rice paddies and temples of the Angkorian civilization below — a hydraulic theology, in a sense, connecting the divine mountain to the empire's agricultural wealth.
Gates' Season 1 investigation introduces viewers to the historical stakes without claiming to resolve them. The episode frames Phnom Kulen as both a living pilgrimage site and an active archaeological frontier, acknowledging that the full story of Mahendraparvata is still being written by researchers in the field. As with many of the earliest Expedition Unknown episodes, the value lies in raising the right questions rather than delivering final answers.
The Kbal Spean riverbed is believed to contain hundreds of lingas carved directly into the sandstone, so that water flowing over them would be ritually consecrated before reaching the temples and rice fields of Angkor below.
Jayavarman II's devaraja — or 'god-king' — ceremony on Phnom Kulen, traditionally dated to around 802 A.D., is credited in later inscriptions with unifying the Khmer people and ending their political subordination to Java.
The name 'Mahendraparvata,' meaning roughly 'Mountain of the Great Indra,' appears in ancient Khmer inscriptions but its precise location on the plateau was largely a matter of scholarly debate until modern remote-sensing surveys began to shed new light.
Phnom Kulen remains an active pilgrimage destination for Cambodian Buddhists, who visit its waterfall and hilltop shrines — meaning any archaeological investigation must navigate the site's ongoing religious significance alongside its ancient history.
Phnom Kulen is generally accessible from Siem Reap, with the journey typically taking one to two hours by road — though road conditions and access fees have historically varied, so checking current local advisories before visiting is strongly recommended. The plateau is an active religious site, and visitors are expected to dress modestly; weekends and Cambodian holidays tend to draw large crowds of local pilgrims. The Kbal Spean riverbed carvings and the large reclining Buddha are among the main points of interest on the mountain.
Siem Reap, approximately 50 kilometers to the southwest.
The dry season — roughly November through April — is generally considered the most practical time to visit, as roads to the plateau can become difficult during the monsoon months. Early mornings on weekdays offer the quietest experience, before pilgrimage crowds and midday heat build.
Cambodia National Museum, Phnom Penh
Gates begins his Phnom Kulen journey in Phnom Penh, and the Cambodia National Museum provides essential context for Khmer history and artifacts — making it a natural companion site within the same episode arc.
Guatemala Snake King Archaeological Sites
Like Mahendraparvata, the Guatemala Snake King sites represent a 'lost' Maya royal center revealed through LiDAR and jungle archaeology — a close methodological and thematic parallel to the Phnom Kulen investigation.
Sky Caves of Nepal
The Sky Caves of Nepal, like Phnom Kulen, combine extreme geographical inaccessibility with sacred significance and an ancient civilization whose origins are still being pieced together by archaeologists, themes Gates returns to repeatedly across the series.