Or, are we dealing with some other biological function that inhibits the reproduction of some haplogroups at that latitude.
The Aryans did invade India, as their ancient tales say they did, but it was a mighty long time ago. There are nationalists in India who dispute this for various reasons. I don’t accept that they “would have wiped out the native ASI population”, but they brought their language with them, and the Indus Valley script, though it hasn’t been deciphered (no bilingual text has been found, perhaps none ever existed), has been shown to convey an agglutinative language, which Dravidian is, and Indo-European tongues are not.
The Indus Valley / Harappan culture was in the north, right where the Aryan migration into India from Central Asia occurred. Regardless of what people that civilization represents, it probably wasn’t Indo-European, and may not have left any discernable legacy (so far — if the script is cracked, perhaps some cultural spit-swapping will be revealed). The Aryans may not have been the agents of that civilization’s destruction (there’s some evidence that the cities were deserted except for the bodies of the dead and the Aryans rode on through).
Samuel Noah Cramer pointed out that the names used for most major cities and the mighty rivers of Mesopotamia were adopted by the Sumerians, but are not Sumerian names; the names appear to be from no known language, so apparently the Sumerians preserved just those few traces of some unidentified earlier people. It would be nice to see if the Harappans did the same thing, but for all we know the Indus Valley seals were part of an accounting system, and the lengthy documents were all on perishable media.