When the Aryans invaded India, they kicked asses of the native dark skinned Dravidian people. As with most invaders, they killed off most the menfolk and raped/enslaved all the womenfolk, creating an increasingly diluted brown majority. Just as in Italy after the Germanic invasions, people in the north are lighter and in the south are darker skinned. The Tamil people in southern India are black skinned with straight hair. Tilak made his arguments based on his understanding of the oldest records which repeatedly indicated a homeland with long seasons plus a centuries long emigration, stopping and staying here and there until they found themselves in the subcontinent, unable to travel further. The white skinned Iranians are in this lineage, even taking their name from their name Aryan. A similar thing happened when the Iliad Hellenes moved south after a global cooling event, settling in Greece and Italy. Read the Iliad some time. It's constantly raining, freezing and snowing. That ain't Greece/Turkey. It was the Baltic Sea. A more dubious story is the archaic records of the origins of the Lenape (Delaware) Indians of New Jersey, having been supposable from Canaan, traveled north to the arctic, travelled east to the Bering Strait and crossed through Alaska, Canada and all of North America until they bumped into the Atlantic one hundred years before the Mayflower event. I recall that their document was called the Red Record, but I mostly forget the details now. Especially delicious to me, part of them in the arctic didn't move east, but later traveled west, crossing into Greenland, then again into Canada and finally dropping down until they bumped into their fellow Algonquin kin of yore. It's all out there online if you care to dig.