I am reading Thant Myint-U’s The Hidden History of Burma: Race, Capitalism, and the Crisis of Democracy in the 21st Century. In it, he mentions the legends and oral history of some Burmese that much of Bengal was once inhabited by people like the modern Burmese: Buddhist, and East Asian in appearance.

I don’t know what to think about these sorts of memories, but after spending a day (for various reasons) looking at mtDNA (direct maternal) and Y (direct paternal) ancestry in various groups: I am more and more convinced it is plausible that much of Bengal was inhabited by a Tibeto-Burman people.

The reason is that in Bangladesh it looks to be that ~10% of the mtDNA and ~10% of the Y chromosomes are East Asian. This is in line with the genome-wide ancestry. To the west and south of Bengal, there are peoples with even more East Asian ancestry, the various Munda tribes. But these groups have a different profile. 30% of their ancestry is East Asian. But 60% of their Y chromosomes are East Asian, while 0% of their mtDNA is East Asian.

One thing we know about the Munda is that they speak Austro-Asiatic languages. Genetically their East Asian component seems to have mixed with people deeply related to the Andaman Islanders, before mixing again with a people with affinities to South Indian tribal people. Additionally, the Munda have almost no “steppe” affinity.  This is curious because this occurs only among some South Indian tribal groups. Even among non-Indo-Aryan South Indian populations, such as the Reddy of Andhara Pradesh, there is some steppe ancestry.

Genetically it seems that the earliest mixing of East Asian and “indigenous” ancestry in the Munda dates to the period between 4,000 and 4,500 years ago. I am now open to the possibility that the Munda arrived in the Indian subcontinent via the Bay of Bengal. And that the northern Munda languages are actually expansions from a southern expanse.

In any case, the situation in Bengal seems to be different. If there were Munda in Bengal, they didn’t leave much of an imprint from what I can tell. The admixture into the Bangladeshi genomes dates to about 1,500 years ago. Rather than an intrusion of Tibeto-Burman people into the plains of Bengal, this may indicate an expansion of Indo-Aryan agriculturalists into the lands of slash and burn Tibeto-Burman agriculturalists.