The Austroasiatic languages, in recent classifications synonymous with Mon–Khmer, are a large language family of continental Southeast Asia, also scattered throughout India, Bangladesh, and the southern border of China. The name Austroasiatic comes from the Latin words for "south" and "Asia", hence "South Asia". Among these languages, only Khmer, Vietnamese, and Mon have a long-established recorded history, and only Vietnamese and Khmer have official status (in Vietnam and Cambodia, respectively). The rest of the languages are spoken by minority groups. Ethnologue identifies 168 Austroasiatic languages. These form thirteen established families (plus perhaps Shompen, which is poorly attested, as a fourteenth), which have traditionally been grouped into two, as Mon–Khmer and Munda. However, one recent classification posits three groups (Munda, Nuclear Mon-Khmer and Khasi-Khmuic) while another has abandoned Mon–Khmer as a taxon altogether, making it synonymous with the larger family.
Austroasiatic languages have a disjunct distribution across India, Bangladesh and Southeast Asia, separated by regions where other languages are spoken. They appear to be the autochthonous languages of Southeast Asia, with the neighboring Indic, Tai, Dravidian, Austronesian, and Tibeto-Burman languages being the result of later migrations (Sidwell & Blench, 2011). Genetic studies of representatives from all branches of Austroasiatic indicate the ancestors of Austroasiatic speakers originated in present-day India and migrated into Southeast Asia from the Brahmaputra River Valley. (from Wikipedia)