"I agree that a plausible explanation has yet to be given as to how, if there were indeed no actual invasion of Indo-Aryans but only the migratory ‘trickle’ into which it has been reconfigured, the newcomers could have completely eradicated the pre-existing language of the entire North of the subcontinent in the short interval normally allotted between their arrival and the composition of the Rgveda, in which the local topography is Indo-Aryan. When one considers that, in these proposed two or three centuries, such hypothetical migrants managed even to Sanskritize practically all of the names of rivers and places, the most conservative aspect of a substratum, in the N.W. of the subcontinent, but yet failed to do so in the East of the subcontinent despite Aryanizing it for well over two millennia, and the accomplishment is remarkable (and, of course, they failed to even displace the Dravidian languages in the South despite extensive interaction for almost as long). Add to this that their predecessors were the highly sophisticated and urbanized residents of the Indus Valley Civilization, and the incoming Indo-Aryans typically construed as pastoralist nomads, and Kazanas has a right to wonder how and why would the Indus Valley dwellers have so thoroughly and completely adopted the language of these illiterate herdsmen if the latter were not invaders — a status denied them by archaeology?"