France conquered most of the Indochinese Peninsula starting with the takeover of the southern city of Saigon in 1862. Soon, France took possession of all the South of the Annamese Empire, along with Cambodia.
By the 1880s, France convinced the Emperor of Annam to put himself under its protection, and a few years later, it took control of all Lao lands, which had been disputed between Annam and Siam for centuries.
French Indochina was then administered as a federation of five entities: Annam, Tonkin, Cochinchine, Cambodia and Laos. This status remained until World War 2, when Japan invaded the peninsula and promised independence to the local elites. When France retook possession of the region after the war, they had to deal with unrest, which turned to a violent war. France had lost control of the region entirely by 1954.
More on French Indochina
The French Conquest of Indochina
