The Third Indochina War was a series of conflicts lasting from 1978 to 1991 over influence in mainland Southeast Asia after the Communist victory in the Second Indochina War. The war was mostly fought between differently-aligned communist nations: Vietnam and Laos, alighed with the Soviet Union, versus Cambodia and its ally China. It is therefore considered a proxy conflict of the Sino-Soviet Split.
The war began in late 1978 after the Khmer Rouge regime in Cambodia carried out several raids into neighboring Vietnam, upon which the People's Army of Vietnam invaded Cambodia, deposed the Khmer Rouge, and then faced a decade-long guerilla struggle to destroy the remnants. In response to the invasion of their ally, China sent the People's Liberation Army into the northern provinces of Vietnam as a punitive expedition in February 1979.
The PLA withdrew from Vietnam in March of 1979, but the PAVN would be fighting in Cambodia until 1989, leading some Western commenters to call the conflict "Vietnam's Vietnam". The conflict was finally ended by a peace agreement in 1991 and the restoration of Cambodian government in 1993.
