The latest research shows that the R1a-Z93 of Sintashta and Andronovo originated from the Corded Ware culture (Middle Dnieper-Fatyanovo-Abashevo). If so, Sanskrit would be unified with Germanic and Balto-Slavic instead of the proposed "Graeco-Aryan".
However, while Sanskrit is closer to Balto-Slavic in “satem”, but at grammatical level (injunctive, augment), Sanskrit should clearly be more closely related to Greek.
How should the conflict between archaeology and linguistics be resolved? Indo-European.eu used to see Corded Ware as Uralic, but that was clearly wrong. In August 2021, Indo-european.eu finally corrected its opinion and agreed with Corded Ware's Indo-European identity.
Another marginal hypothesis is that the Corded Ware Z93 of Fatyanovo-Abashevo, originally speaking Northwestern Indo-European languages, later chose Aryan languages and Aryan cultures such as horse sacrifice in Z2103 Poltavka, but somehow had little genetic influence.
Also, more information about Fatyanovo and Abashevo is mainly located in a thread discussing Indo-European loanwords in Finno-Ugric languages, in Anthrogenica. Uralic and Proto-Indo-Aryan interacted in this region.
I had mistakenly considered the close connection between Sarmatians and Balto-Slavs, mainly because classic Indo-Iranian cultural terms (Vajra, Yama, Asura, etc.) were not found in Scythian and Sarmatian mythology. Instead, these terms only appear in Vedic and Avestan, and even in Uralic (Uralic loanword for Asura is Asera, which takes s rather than h, and is closer to Indo-Aryan). In Wikitionary, this could be found.
However, I abandoned this idea when I discovered that both Scythians and Sarmatians had some degree of East Eurasian admixture and could not be the direct ancestors of Slavs. They are still (fused with Karasuk) Northern Iranians. But the gap between northern Iranian nomads' mythology and classic Indo-Iranian mythology of the south is still my doubt.
Besides, Anthrogenica still mentions that Sintashta and Andronovo (especially the northeast) lack Indo-Aryan haplogroups (R1a-Y3, L657, etc.), which are all later North Iranian nomads' Haplogroup (eg R1a-Z2124-S23592). So, in general, Proto-Indo-Aryans should have originated in northern forest steppe, had cultural contact with Finno-Ugric people, but remained a cultural gap with Scythians and Sarmatians (only contacted with Avestan Iranians) , which is a complex issue. Anthrogenica mentions a hypothesis: Indo-Aryans started out as a relatively small wave that quickly entered BMAC from the Volga-Ural region without leaving much archaeological remains.
