The Thai language developed from the Tai–Kadai languages, also known as Kra–Dai, Daic, and Kadai, are a language family of highly tonal languages found in southern China, northeast India and Southeast Asia, but Thai is not related to Chinese.

The Thai language developed from the Tai–Kadai languages, also known as Kra–Dai, Daic, and Kadai, are a language family of highly tonal languages found in southern China, northeast India and Southeast Asia, but Thai is not related to Chinese.

Indochina was a French colony, so the official language of administration was French. The native peoples of Indochina had a wide variety of languages. The Vietnamese, who were the largest Indochinese population, spoke Vietnamese, which is an Austroasiatic language. Khmer, the dominant language of Cambodia is also Austroasiatic. Lao, which is dominant in Laos is a Tai-Kadai Language. There were also ethnic minorities who spoke Sino-Tibetan Languages, Austronesian Languages, and Hmong-Mien Languages.