I meant to post this earlier and in any case Anita has posted it..
The Aryans came from outside India. We actually have genetic evidence for that. Very clear genetic evidence from a marker that arose on the southern steppes of Russia and the Ukraine around 5,000 to 10,000 years ago. And it subsequently spread to the east and south through Central Asia reaching India. It is on the higher frequency in the Indo-European speakers, the people who claim they are descendants of the Aryans, the Hindi speakers, the Bengalis, the other groups. Then it is at a lower frequency in the Dravidians. But there is clear evidence that there was a heavy migration from the steppes down towards India. Dr Spencer Wells – Rediff Interview.
In a sane and rational world evidence from genetics would be conclusive evidence that proves the Aryan Migration Theory (not “invasion"
But we are not in a sane or rational world, so people will continue to argue.
But there is an interesting question: When the Dravidians migrated, why did they migrate down south? Why didn’t they migrate to the Gangetic plain from the Indus valley? The latter is a much more fertile area right?
Dravidians settled first in the northwest and from there they spread out through out India.But when aryans came on the scene after the decline of IVC,they were all overwhelmed.