Indian tradition has the Aryan invasion coming from the north and pushing the original inhabitants to the south. The pattern of languages on the subcontinent today supports that scenario, with Dravidian (non-Indoeuropean) languages in the south and in Sri Lanka, but only in a pocket or two in the north where Hindi and other descendants of Sanskrit predominate.
This "Indian origin" thing resembles the idea put out in this country that Ancient Egypt was peopled by blacks. That is, it's a modern invention to encourage ethnic pride. Perhaps next the Brits will decide that the Norman invaders may have come from Scotland or Wales.
Editor wanted. Must work for peanuts.
Actually rather than a nationalistic concept, Hindus believe that the Aryans were of indian origin and that the ancestors of some northern indians (Aryans) were not invaders.