A follow-up to my previous post, one of the “Iron Age” samples from Thailand seems a definite outlier in comparison to the other Iron Age and Bronze Age samples. There is suggestive evidence again of Indian ancestry, as one sees in the plot above. One of the samples from Thailand overlaps with the Cambodians and Burmese, who do seem to have South Asian shift, while the other samples from Thailand do not. Today most Thais seem to show some Indian ancestry as well, at low levels.
Unfortunately, much of Southeast Asian history before 1000 A.D. is pretty much a cipher. Perhaps the best survey I’ve seen is Strange Parallels: Volume 1, Integration on the Mainland: Southeast Asia in Global Context, c.800–1830, though even there it’s rather thin before the arrival of the Tai and the shocks that entailed for the earlier Indic societies of Southeast Asia.
Interesting, which sample is the outlier? There were several Thai Iron Age samples from McColl et al and one from Lipson et al IIRC, the former from Long Long Rak in the extreme northwest, almost in Myanmar, and the latter from Ban Chiang in the far northeast of the country.
The Hoabinhian/Jehai samples appear to be slightly closer to the East Eurasian cluster than to the Tamil or Andamanese clusters. They’re just to the right the origin on the PCA. I wonder which PC component(s) would separate genuine Hoabinhian ancestry from Onge or AASI in SE Asians.
i think the jehai have austronesian ancestry