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?
