Tonkin, officially the Republic of Tonkin, was a short-lived semi-Marxist state in Indochina that existed officially between May 5, 1988 and October 17, 1997, when it was reunited with Vietnam following the fall of Saigon. However, Tonkin existed semi-officially from 1967 and onwards, when the proposed breakaway state was first suggested by the Communist Party of Vietnam, which exerted considerably more power in the north than in the Westernized south. Tonkin was inexorably tied to Chinese goals, and despite China's strict anti-Communist policy, they supported Tonkinese rebels during a thirty-year period, hoping to gain influence throughout Indochina, which it viewed as its personal backyard. The earliest proposal for a Tonkinese state was in 1946, after the American withdrawal from Saigon, when Ho Chi Minh, one of the local governors of Hanoi, suggested that the Western sensibilities of the South were incompatible with the agrarian, traditional north, and thus they should exist as two states, a view only partially endorsed by China.
The capital of Tonkin, both unofficially and officially, was Hanoi, the north's largest city and later Vietnam's third-largest after Saigon and Hue.