A reader pointing me to a paper whose hypothesis is novel to me. But, I have to say that reading the paper, I am now convinced this is highly likely. The paper is The Munda Maritime Hypothesis:
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.
For me, the Brahmaputra migration always implied that Bangladeshis should have lots of Munda ancestry. And yet that is not clear from genetics (though a few individuals are shifted in that direction). In contrast, they do have a strong affinity to the Khasi. This paper proposes that the Khasi are quite distinct from the Munda.
Rather, the Munda are placed further south, and their arrival in South Asia was through maritime means. 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…
If Bangladeshis have little munda, that means most of AASI in Bangladeshis are from IVC? Some additional AASI was absorbed during eastward migration, in the gangetic plains.
Can Bangladeshis be modelled as 50% Iranian, 25% AASI, 15-16% Steppe, 10% NE Asian and 2-5% Munda? Those few Bangladeshis that have some munda ancestry are probably from North Bengal(Rajshahi/Rangpur area) as those are the only region in Bangladesh that have few Santhal/Munda settlements. I guess prior to the migration of proto-Bengalis in eastern Bengal, the region(except Varendra) was inhabited by Garo/Khasi and Tripuri like east Asians. I would like to see the comparison between Bengalis and their closely related neighbours like Odias and Assamese. I suppose, Assamese are more East Asian shifted and their East Asian is mostly if not fully northeast Asian related. The Odias must have some east Asian and their east Asian might be fully Munda related. Also the Bengalis from Midnapore,West Bengal near Jharkhand border might have only Munda type east Asian.
“Aryan conquest in the Iron-Age”. lol
kevin, the residual non-east asian asian looks like what you find in bihari peasants.
A positive point from my perspective is means you have more space to explain why Munda don’t have ancestry that is probably related to Sino-Tibetan speakers moving south into what is today Myanmar.
Such ancestry appears to probably arrives in NE Myanmar (at the Oakaie site) by at least 3200-2700 BP by adna finding a North China related ancestry profile with some probably Austroasiatic speaker related ancestry (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6476732/)… and about the same time using Bayesian phylogeny on a Sino-Tibetan lexical cognacy set (https://www.pnas.org/content/116/21/10317). That’s relatively “tough” when Austroasiatic related ancestry is in Vietnam only about 500 years earlier by the adna (possibly slightly earlier in ground truth, but not necessarily hugely earlier, if we assume that this was an expansion archaeologically associated with neolithic farming).
Of course, there’s no reason why you could not simply have no reproduction between such populations prior to proto-Munda speakers migrating to India and a very fast train to India, or you could have any Sino-Tibetan related ancestry being “swallowed up”.
But the former is more plausible in situations where we don’t find admixing in the first ancient samples sequenced (as is the case at Oakaie) and in the latter more plausible where you have relatively large and geographically distributed populations to “absorb”, which seems not so much the case in mainland SE Asia of this time(?).
Although I by no means would rule out anything based on the above, it’s possibly “easier” if a migration to India simply happened over the seas from a point that Austroasiatic speaking cultures had reached, but Sino-Tibetan speaking cultures had not. (NB: The challenging point is of course “Yes, all this is fine, but did they actually have the maritime technology for this?”.)