The Rig Veda does provide important evidence of a migration, but not by narrating it. Rather, the vocabulary, grammar, and mythological content are so similar to the Avestan texts that a common linguistic origin seems inescapable. That of course doesn't demonstrate population replacement on its own, but lacking Starlink or even homing pigeons, some kind of migration was clearly involved.
Do we know it's steppe ancestry because of DNA comparisons with Kurgan grave DNA, or from some other evidence? To me it seems a priori difficult to know where a gene hails from originally.
That’s a great question but I don’t know how this gene flow worked. I’m not an expert in genetics but genetic research shows that one component of Indian DNA matches with Steppe Pastorals.
If in earlier periods a specific haplogroup is concentrated in specific relatively small area but after a couple of centuries it can be found across the entire continent that seems like a good indicator.
That's why I was asking if this conclusion is based on grave DNA data. How else do you know where haplogroups were in earlier periods, other than by already knowing the information about historical migrations and population replacements that we're trying to derive in the first place?
The Rig Veda does provide important evidence of a migration, but not by narrating it. Rather, the vocabulary, grammar, and mythological content are so similar to the Avestan texts that a common linguistic origin seems inescapable. That of course doesn't demonstrate population replacement on its own, but lacking Starlink or even homing pigeons, some kind of migration was clearly involved.