The biggest French colony outside Africa and the one with the highest population (over 22 millions in 1940), French Indochina comprises Annam, Cambodia, Cochin-China, Laos, and Tonkin. There's unrest in the lands, especially in the Vietnamese East, where the Nationalists and the (albeit split between Stalin and Trotsky) Indochinese Communist Party are active, especially a certain Ho Chi Minh. That's why France appointed General Georges Catroux - he is the first Military governor of the colony since administration by civilians was introduced there in 1879. He is holding the natives down with 12,000 French and 40,000 native soldiers, plus the Sûreté police. There aren't many French civilians around, only a few ten thousands.
Most of the population is Buddhist, although Roman-Catholic missionaries have managed to convert about 10% of the population. Additionally, there are odd sects like Caodaism, which is a mixture of Christianity, Confucianism and Buddhism. They have a pope, female cardinals, and even worship e.g. Victor Hugo as a saint.
When the Wehrmacht defeated France in June 1940, the country had to hand over the control of the colony's border to China to Japan - to prevent the Transit of Weapons.