http://www.yhrd.org/Search/Populations

Characteristically, most of the DNAs are R1a1a some J, some G, and some L.

R1a1a is the main west eurasian marker in pretty much all of north south asians, I am just wondering who spread this genetic marker?

I find it hard to believe that it was spread by indo aryans alone. There is no way this marker can be found so deep with in India, if it was spread by indo aryans alone, Either it is really ancient, or it was spread by a massive movement of people towards south asia at some point that we dont know about, there is currently very little historical data to back any kind of such movement. I personally believe that it may be very ancient

I think during the course of 3000+ years now, R1a1 could have been spread by indo-aryans and iranic people, as well as some others, and it could also get deep into India in that time span.

I have also read that the R1 group might have originated in India a long time earlier - 40,000 or whatever years ago.

Interestingly there was a newspaper article in UK some years ago (i have a copy of it) that 1 in 5 white British had direct black ancestory. That resulted from the slave trade, despite there not having been a huge percentage population of black slaves in the UK, and it is before the current racial mixing happening in UK right now due to immigrants in the 20th century.