The field has advanced incredibly since then - uniparental markers like mitochondria or Y are a helpful clue, but we have so much genome wide information now. Indian population genetics is still in its infancy, though, since Indian government rules around the export of biomaterial means only Indian labs can work on them, and honestly most of them have strong biases they're looking to confirm. So much of the Indian population information in databases is simply extrapolated from tiny, non-representative samples collected from Indians abroad.