Province. Other protected areas are Phu Chong-Na Yoi National Park, Khao Phra Wihan National Park, Yot Dom Wildlife Sanctuary, Huai Sala Wildlife Sanctuary, Hua Tabtan Hadsamran Wildlife Sanctuary and Ta Phraya National Park on the Thai side, as well as Banteay Chhmar Protected Landscape, Preah Vihear Temple Protected Landscape and the Preah Vihear Protected Forest on the Cambodian side. History The Dângrêk Mountains were part of the ancient Khmer Empire, which spread northwards across them, culminating with the almost complete control of the Isan area in 1220 under Jayavarman VII. Among the archaeological remains in the mountain area there are stone carvings on the Pha Mo I-Daeng cliff, ancient stone-cutting quarries, as well as the Sa Trao reservoir. There are also remains of sanctuaries that were built as homes to spirits called phi ton nam ('watershed spirits') in different spots along the border area of the Dângrêk mountain chain. However, the largest and most important archaeological site in these mountains is the Prasat Preah Vihear compound, a Shaivite temple of the Khmer imperial times dated from the reign of Suryavarman I in a dramatic location on top of a high hill. In 1975, following the fall of the Lon Nol regime on 17 April the Khmer Rouge entered the capital Phnom Penh. But the final area held by the ill-fated Khmer Republic in any form would be the Preah Vihear Temple in these mountains. Khmer National Armed Forces occupied the place in late-April that year. They held on for a few weeks until the hill where the temple stands was finally taken by the Khmer Rouge on 22 May. Between 1975 and 1979 many Cambodians fled the violence in their country across these mountains. In one of the worst cases of enforced repatriation in UN history, the Thai military forcefully sent as many as 40,000 refugees back into Cambodia often through heavily mined areas despite their unwillingness to return. Many would die of lack of food and exposure in the mountains. To compound matters, there were also bandits hiding in the forests preying on the hapless refugees. At that time there were many corpses, lying rotting unburied, strewn about the Dângrêk Mountains. In the 1984 movie The Killing Fields, the Dângrêk Mountains are the final escarpment that Pran, portrayed by actor Haing S. Ngor, climbs in order to reach the safety of the refugee camp across the border in Thailand.