In 1975, the Khmer Rouge captured power over the US supported Lon Nol government. Thus began a nightmare which saw Cambodian killing Cambodian. The killings only stopped after Vietnam invaded Cambodia in 1979 as a result of a border dispute. Many people say Vietnam should not have invaded Cambodia. However, history revealed that this act saved the Cambodians from further killings by the Khmer Rouge. The Vietnamese invasion triggered a war with China at the Viet-Chinese border......but that is another story. China-Vietnam War 1979 : http://www.youtube.com/watch?v=ECbhcqdIN5g