Indochina is a region in Southeast Asia that includes several countries. The term "Indochina" refers to the intermingling of Indian and Chinese influences in the culture of the region. The countries that make up Indochina are Vietnam, Cambodia, Laos, Myanmar, Thailand, and western Malaysia. The notion of a single entity called Indochina originated with French colonization, which began in the 17th century. The French created the first Indochinese Union to govern the region, which included Vietnam, Laos, and Cambodia. The French later formed 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 conflict known as the First Indochina War soon erupted, and the French lost control of the region. Today, Indochina is not used as commonly as "Mainland Southeast Asia".

In summary, Indochina is a region in Southeast Asia that includes several countries, and the term refers to the intermingling of Indian and Chinese influences in the culture of the region. The countries that make up Indochina are Vietnam, Cambodia, Laos, Myanmar, Thailand, and western Malaysia. The notion of a single entity called Indochina originated with French colonization, which began in the 17th century.