India's Aryan invasion theory, probably true suggest two DNA studies.

It turns out that the Aryans were of European origin and that they did invade India and impose a caste system.

As you may know a caste system operates in India, dna taken from the 3 main castes has shown that as you go from lower castes to higher castes the percentage of European dna increases.

"Our results demonstrate that for biparentally inherited autosomal markers, genetic distances between upper, middle, and lower castes are significantly correlated with rank; upper castes are more similar to Europeans than to Asians; and upper castes are significantly more similar to Europeans than are lower castes."

The Aryan invasion theory is seen as a thorn in India's side by many Indians however the genetic and particularly the Y-dna results are showing the footprint of an invading predominantly male European force.

[link to www.ncbi.nlm.nih.gov]

Meanwhile another genetic analysis of a Dravidian tribe in South India has also found significant European DNA input.

"According to the allele frequency of Y-STR, the Ezhavas were genetically more similar to the Europeans (60%) than to the East Asians (40%).

CONCLUSION:

The vast majority of haplotypes were observed only once, reflecting the enormous genetic heterogeneity of the Ezhavas. Based on the genotype, the Ezhavas showed more resemblance to Jat Sikh population of Punjab and the Turkish populations than to the East Asians, hence indicating a paternal lineage of European origin."

[link to www.ncbi.nlm.nih.gov]