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.
Each of the families that is written in boldface type below is accepted as a valid clade. By contrast, 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. However, little of the data used for competing classifications has ever been published, and therefore cannot be evaluated by peer review.
In addition, there are suggestions that additional branches of Austro-Asiatic might be preserved in substrata of Acehnese in Sumatra (Diffloth), the Chamic languages of Vietnam, and the Land Dayak languages of Borneo (Adelaar 1995).
Read more about this topic: Austro-Asiatic Languages