Felix Rau and Paul Sidwell, "The Munda Maritime Hypothesis" (2019).On the basis of historical linguistic and language geographic evidence, the authors advance the novel hypothesis that the Munda languages originated on the east coast of India after their Austroasiatic precursor arrived via a maritime route from Southeast Asia, 3,500 to 4,000 years ago. Based on the linguistic evidence, we argue that pre-Proto-Munda arose in Mainland Southeast Asia after the spread of rice agriculture in the late Neolithic period, sometime after 4,500 years ago. A small Austroasiatic population then brought pre-Proto-Munda by means of a maritime route across the Bay of Bengal to the Mahanadi Delta region – an important hub location for maritime trade in historic and pre-historic times. The interaction with a local South Asian population gave rise to proto-Munda and the Munda branch of Austroasiatic. The Maritime Hypothesis accounts for the linguistic evidence better than other scenarios such as an Indian origin of Austroasiatic or a migration from Southeast Asia through the Brahmaputra basin. The available evidence from archaeology and genetics further supports the hypothesis of a small founder population of Austroasiatic speakers arriving in Odisha from Southeast Asia before the Aryan conquest in the Iron-Age.
Razib Khan has helpful commentary. He notes genetic evidence disfavoring the conventional wisdom that the Munda arrived further north in India by land. In part that is because we normally think of the Austroasiatic people (the most famous Austroasiatic language today is Vietnamese), as land oriented farmers, in contrast to the maritime oriented Austronesians (derived from Taiwan and the settlers of many of the islands in the Pacific Ocean, New Zealand, and island Southeast Asia, as well as Madagascar). He also adds that:
One of the possibilities suggested is a relation to the Aslian subgroup of Austro-Asiatic languages in central Malaysia. This could actually help explain the enrichment for AASI in the Munda: the indigenous Negritos of Malaysia are similar to the people of the Andaman islands!
Remember, the arrival of Austro-Asiatic farmers in northern Vietnam dates to ~4,000 years ago. The Munda could be relative latecomers to South Asia…
I agree that the hypothesis is a plausible one, and represents yet another extreme localization of the remote origins of a language or language family akin to the likely pin point origins of the proto-Austronesians (to a subregion and indigenous tribe of the island of Formosa), the Austronesian settlers of Madagascar (from a specific part of the island of Borneo where a specific dialect is spoken), the Bantu people (from a county sized area on the Nigerian coast), and in my opinion, also the Chadic languages (from a county sized area of modern day Moldova).