France obtained control over northern Vietnam following its victory over China in the Sino-French war (1884-1885). French Indochina was formed in October 1887 from Annam, Tonkin, Cochinchina (which together form modern Vietnam) and the Kingdom of Cambodia following the Sino-French War (1884-1885); Laos was added after the Franco-Siamese War. The federation lasted until 1954. In the four protectorates, the French formally left the local rulers in power, who were the Emperors of Vietnam, Kings of Cambodia, and Kings of Luang Prabang, but in fact gathered all powers in their hands, the local rulers acting only as figureheads. In Cochinchina the administration was under a prefect and a French bureaucracy.

In 1940, the Japanese troop occupied the Tonkin area of northern Vietnam and in the following year the rest of Indochina. However, apart from Vietnam and the western provinces of Cambodia, which the Japanese ceded to their Thai ally. Indochina was not affected by the Japanese invasion very much. The local French Vichy government was even accepted to remain in office until March 1945, when the Japanese interned the local French personnel and proclaimed the fact that Vietnam became an autonomous state.

This regime collapsed after the Japanese troop had surrendered to the Vietnamese troop in August 1945. At the same time, in the north the party called the Viet Minh under the Vietnamese great nationalist leader Ho Chi Minh at once proclaimed a Democratic Republic of Vietnam and assumed power on September 2, 1945 at Hanoi Ba Dinh Square. In the meantime, because the monarchies in Laos and Cambodia hesitated to follow suit, the French soon reoccupied the two states. In turn, the French established the Indochinese Federation, which was to be part of a new, greater French Union and in which the Democratic Republic of Vietnam was to be treated as an independent state. However, the French Union was not established for several years, and then it provided for control of the area from Paris.

The conflict called the First Indochina War soon erupted, in the lull in the fighting between 1949 –1950, the French with an aim to retain their holdings in the area, ratified separate treaties that recognized Vietnam, Laos, and Cambodia as independent, self-governing states within the French Union. Ultimately, the conception that these states were united to form “French Indochina” completely came to an end. Nevertheless, the leaders of the states were viewed as puppet rulers, and real independence did not come to the region until after the Geneva Conference of 1954, which finally ended the fighting between the French and the Viet Minh. Thus, the term of Indochina originated from the way that the French often called in the time at which they administered the region.