[citation needed] Command of water played an important role in the rise and fall of Angkor, and scholars using satellite technology are only now beginning to fathom the true size and achievement of medieval Khmer society.
Once abandoned after the reign of Suryavarman II, stagnating reservoirs attracting mosquitoes may have been the cause spreading malaria as this was also the period in which this disease was introduced in Southeast Asia.
[2] Groslier argues the fall of Angkor was partly brought on by an imbalance in the ecosystem that was caused by the extension of irrigated rice fields and hydraulic cities into formerly forested land in Cambodia, and was therefore an ecological crisis induced by mankind.
Some scholars have connected the decline of Angkor with the conversion of the Khmer Empire to Theravada Buddhism following the reign of Jayavarman VII, arguing that this religious transition eroded the Hindu concept of kingship that underpinned the Angkorian civilization.
[8] Brendan Buckley suggests this drought dried out Angkor's reservoirs and canals,[9] which in turn, led to its precipitous decline and foreign invasion.
[2] Climate change may have been another factor in the fall of Angkor which happened during the transition from the Medieval Warm Period to the Little Ice Age.
[10] Contrary to the popular idea that ancient temple complexes had been abandoned after the fall of Angkor, many important sites remained in use, although now they were rededicated to the Theravada cult.