Cambodia By adam12clear. 556 Buddhism was founded from the teachings of Siddhartha Gautama, BC Jan 1, 1400 600 years powerful Khmer kings dominate much of presentday Southeast Asia, Jan 1, 1941 the throne switched back Aug 17, 1945 Cambodia's current king, Norodom Sihanouk. He was 18. In 1945 Jan 1, 1989 the Vietnamese withdrew the last of their troops and the government renamed the country State of Cambodia