The Austro-Asiatic languages are a large language family of Southeast Asia, and also scattered throughout India and Bangladesh. The name comes from the Latin word for "south" and the Greek name of Asia, hence "South Asia." Among these languages, only Vietnamese, Khmer, 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 Austro-Asiatic languages. These are traditionally divided into two families, Mon-Khmer and Munda, but two recent classifications have abandoned Mon-Khmer as a valid node, although this is tentative and not generally accepted.

Austro-Asiatic languages have a disjunct distribution across India, Bangladesh and Southeast Asia, separated by regions where other languages are spoken. It is widely believed that the Austro-Asiatic languages are the autochthonous languages of Southeast Asia and the eastern Indian subcontinent, and that the other languages of the region, including the Indo-European, Kradai, Dravidian and Sino-Tibetan languages, are the result of later migrations of people. There are, for example, Austro-Asiatic words in the Tibeto-Burman languages of eastern Nepal. Some linguists have attempted to prove that Austro-Asiatic languages are related to Austronesian languages, thus forming the Austric superfamily.

The Austro-Asiatic languages are well known for having a "sesqui-syllabic" pattern, with basic nouns and verbs consisting of a reduced minor syllable plus a full syllable. Many of them also have infixes.

Classification

Linguists traditionally recognize two primary divisions of Austro-Asiatic: the Mon-Khmer languages of Southeast Asia, Northeast India and the Nicobar Islands, and the Munda languages of East and Central India and parts of Bangladesh. However, no evidence for this classification has ever been published, and it is possible that the linguistic classification has been influenced by researchers' subjective perception of a racial dichotomy between the speakers of languages that have traditionally been classified as Mon-Khmer and those that have traditionally been classified as Munda.

Each of the families that is written in boldface type below is accepted as a valid clade. However, the relationships between these families within Austro-Asiatic is debated; in addition to the traditional classification, two recent proposals are given, neither of which accept traditional Mon-Khmer as a valid unit. It should be noted that little of the data used for competing classifications has ever been published, and therefore cannot be evaluated by peer review.

Gérard Diffloth (2005)

Diffloth compares reconstructions of various clades, and attempts to classify them based on shared innovations. As a schematic, we have:

{{clade
|label1=Austro- 
Asiatic 
|1={{clade
|label1= Munda 
|1=
|label2= Khasi- 
 Khmuic 
|2=
|label3= (Nuclear)   
|3=
}}
}}

Or in more detail,

• Munda languages (India)

• Khasi-Khmuic languages (Northern Mon-Khmer)

• Nuclear Mon-Khmer languages

Ilia Peiros (2004)

Peiros is a lexicostatistic classification, based on percentages of shared vocabulary. This means that a language may appear to be more distantly related than it actually is due to language contact, so it is only a starting point for a proper genealogical classification.

• Nicobarese

• Munda-Khmer

• *Munda

• *Mon-Khmer

• **Khasi

• **Nuclear Mon-Khmer

• ***Mangic (Mang + Palyu) (perhaps in Northern MK)

• ***Vietic (perhaps in Northern MK)

• ***Northern Mon-Khmer

• ****Palaungic

• ****Khmuic'

• ***Central Mon-Khmer

• ****Khmer dialects

• ****Pearic

• ****Asli-Bahnaric

• *****Aslian

• *****Mon-Bahnaric

• ******Monic

• ******Katu-Bahnaric

• *******Katuic

• *******Bahnaric

Diffloth (1974)

Diffloth's widely cited original classification, now abandoned by Diffloth himself, is used in Encyclopædia Britannica and—except for the breakup of Southern Mon-Khmer—in Ethnologue.

• Munda

• *North Munda

• ** Korku

• **Kherwarian

• *South Munda

• **Kharia-Juang

• **Koraput Munda

• Mon-Khmer

• *Eastern Mon-Khmer

• **Khmer (Cambodian)

• **Pearic

• **Bahnaric

• **Katuic

• **Vietic (includes Vietnamese)

• *Northern Mon-Khmer

• **Khasi (Meghalaya, India)

• **Palaungic

• **Khmuic

• *Southern Mon-Khmer

• **Mon

• **Aslian (Malaya)

• **Nicobarese (Nicobar Islands)

Protolanguage

Sidwell (2005) reconstructs the consonant inventory of proto-Mon Khmer as follows:

This is identical to earlier reconstructions except for , which is better preserved in the Katuic languages which Sidwell specializes in than in other branches of Austro-Asiatic.