So what I've heard is that they were nomadic so there were zero women in the group and they intermixed with the women of the place they settled, thus today's indians almost look alike. If you pick a person of indigenous tribe and a person of brahman community they'll look the same their gene pool will be same almost, the r1a haplogroup is present in indigenous people and also in brahmans, it what makes them how they are. i find this very funny, and yet they wonder why we call them all the same.