VietnamVietnam was part of Imperial China for over a millennium, from 111 BC to 938 AD. The Vietnamese became independent from Imperial China in AD 938, following the Vietnamese victory in the Battle of Bạch Đằng River. Successive Vietnamese royal dynasties flourished as the nation expanded geographically and politically into Southeast Asia, until the Indochina Peninsula was colonized by the French in the mid-19th century. Following a Japanese occupation in the 1940s, the Vietnamese fought French rule in the First Indochina War, eventually expelling the French in 1954. Thereafter, Vietnam was divided politically into two rival states, North and South Vietnam. Conflict between the two sides intensified, with heavy intervention from the United States, in what is known as the Vietnam War. The war ended with a North Vietnamese victory in 1975.