INDOCHIANA (From Wikipedia)

Indochina, or the Indochinese peninsula, is a region in Southeast Asia. It lies roughly east of India, southwest of China. The name has its origins in the French, Indochine, as a combination of "India" and "China", and was adopted when French colonizers in Vietnam began expanding their territory to bordering countries.[citation needed]

Mainland Southeast Asia contrasts with Maritime Southeast Asia, mainly through the division of largely land-based lifestyles in Indochina and the sea-based lifestyles of the Malay and Philippine archipelagoes, as well as the dividing line between the Austroasiatic and Sino-Tibetan languages (spoken in Mainland Southeast Asia) and Austronesian languages (Spoken in Maritime Southeast Asia).

Historically, the countries of mainland Southeast Asia received cultural influence from China and India, but to varying degrees. Some Southeast Asian cultures, such as those of Cambodia, Laos, Myanmar and Thailand are influenced mainly by the culture of India with a smaller influence from the culture of 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.

Today, most of these countries also show pronounced Western cultural influences which began during colonialism of western countries in Southeast Asia.

In a strict sense, Indochina comprises the territory of the former French Indochina:

Cambodia
Laos
Vietnam

However, in a wider sense, the cultural region is better described as Mainland Southeast Asia in which sense it also includes:

Myanmar (formerly Burma—part of British India until 1937)
Singapore (also considered part of Maritime Southeast Asia if the Johor-Singapore Causeway is not taken into account)
Thailand (formerly Siam)

Note that the term Sino-Indian is used to describe things relating to India and China. (e.g. Sino-Indian relations).