Kumar V, Wang W, Zhang J, et al. Bronze and Iron Age population movements underlie Xinjiang population history. Science. 2022;376(6588):62-69. doi:10.1126/science.abk1534
New mammoth paper containing 201 ancient samples from Xinjiang got published recently. Although I do not have access to the main paper yet, I did go through the supplement file and excel data which has most of the technical information about the samples.
An in depth analysis of all the samples is out of the scope of this post, I will just leave a few generic thoughts about them here.
1. Early bronze age samples (pre 2000 Bce) have ancestry from Afanasievo, Tarim Basin and minor BMAC.
2. Late bronze age samples between 1500-1000 Bce are mostly similar to Sintashta_MLBA with minor addition of other ancestries.
3. For Iron age samples, in general they lie on a cline between Sintashta/Andronovo and east asian ancestry from Mongolia Slab grave culture. With some samples closer to Andronovo/Sintashta and other samples heavy on the east Asian ancestry.
4. All these Iron Age samples have additional ancestry from either BMAC, Afanasievo, Tarim Basin or Swat (SPGT), or all of them. In short, the samples are all over the place.
5. None of the samples are confirmed archaeologically to be Tocharian speakers, so in my mind all 3 external ancestries - Afanasievo, Andronovo & BMAC could be a source for Tocharian. I prefer Andronovo as the Tocharian source, with BMAC ancestry providing Bactrian & Sogdian loanwords to Tocharian, but that's just a hypothesis.
6. The SPGT like ancestry from the Indian subcontinent almost definitely provided the Sanskrit loanwords, Buddhist culture and Brahmi script to Xinjiang in the iron age.
7. Bronze age male samples are mostly R1b+, possibly related to Afanasievo, with few Q1+ samples.
8. 3 males samples from the LBA, 1 is R1a-Z2124+ (from andronovo), another is supposedly R1a-Z280+ (European) and 3rd one belongs to Q. Suggests increased andronovo related influence, which is also seen autosomally.
9. Among the male IA samples, there are many Q1+, many J2+, J1+ and central/east asia specific R1b-PH155 samples. Amongst the R1a samples, most if not all are of the Sintashta/andronovo kind, ie Z2124+ (R1a1a1b2a2+). One of the samples is of the Indian subclade R1a-Y3+ (R1a1a1b2a1+) and possibly even L657+. Given that most of Indian subcontinent R1a is L657+ (>80%) whereas most of andronovo related samples are Z2124+ (> 90%), andronovo does not seem to be a direct source of the L657+ Y hg in the Indian subcontinent.
10. Basic 2D PCA of the Xinjiang samples below. 3D PCA will present these complex ancestries more accurately. Most of the samples fall roughly between Sintashta and Mongolia_slabgrave, with additional ancestries from BMAC, SPGT, Afanasievo and Tarim_EMBA.
