Indochina or Indo-China is a peninsula in Southeast Asia lying roughly southwest of China, and east of India. The name has its origins in the French Indochine as a combination of the names of "India" and "China", referring to the location of the territory between those two countries, though the majority of people in the region are neither Chinese nor Indian. The term may also be used in biogeography for the "Indochinese Region", a major biogeographical region within the Indomalaya ecozone.

The countries of mainland Southeast Asia received cultural influence from both India (particularly the Hindu culture) and China to varying degrees. Some cultures, such as those of Cambodia, Laos, Myanmar and Thailand are influenced mainly by India with a smaller influence from China. Others, such as Vietnam, are more heavily influenced by Chinese culture with only minor cultural influences from India, largely via the Champa civilization that Vietnam conquered during its southward expansion.

The historical term French Indochina was a federation of French colonies and protectorates, that France named Cochinchina, Tonkin, Annam, Laos and Cambodia. France had an imperial presence in the region between 1884 and 1954. France withdrew from southeast Asia following the loss of the Indochina War.

Indochina had boundaries imposed by France as a result of military conquests in the region, encompassing areas that are now modern Cambodia, Laos, and Vietnam. The subjects of the colony were not homogenous; rather, Indochina was a "separate entity, it was largely unrelated to the cultural, geographical, and racial elements which shaped the people and governments of its constituent parts".