In other words, the preprint observes that the migration from the steppes to South Asia was the source of the Indo-European languages in the subcontinent. Commenting on this, Rai said, “any model of migration of Indo-Europeans from South Asia simply cannot fit the data that is now available.”
At this point, we need to move to other things. I think the broad genetic framework is pretty clear.
1) The Indus Valley Civilization (IVC) people were a mix of eastern West Asian (from modern Iran) people and native South Asian peoples (~80% of South Asian mtDNA are haplogroup M).
2) ~1500 BC a major incursion from the steppe occurred and overlaid upon #1 to various extents as a function of region, language, and caste.
3) ~0 to 500 AD the strong endogamy that characterizes modern South Asians seems to have established itself.