My SNP test results were out little while ago. I'm M124+ and that means I belong to Y-Haplogroup R2 lineage.
This lineage is mostly confined to South Asia also observed in small frequency in nearby Central Asian and Caucasian regions. However, couple of groups viz. Kurds in Georgia, Chechens carry this lineage substantially. May be due to genetic drift(I'm not sure if I used it properly).
In the subcontinent, its highest occurence is among Eastern(West Bengalis) people and among Sri Lankans( big chunk of Srilankan males have Eastern origins). May be around 20%. Its occurrence among Bangladeshis is unknown.
However, it would be interesting to see how many Andhrites, Biharis and UP-wallahs carry this lineage. That would vary its present frequency in India which is now at 10%.
In South, only Tamils have been sampled for this lineage. The frequency may be around 5-6%. I wonder about Karnataka and Kerala
Well, it is kind of tough to calculate the exact frequency of the haplogroups in Indian context. Here almost all the studies are caste based. However, I'm not sure if there is a consistency in defining the upper/middle/lower castes and also if there is a proper data on what percentage of the population belongs to any of those.
Pakistan and North-West India probably have it at around 8-10%.
I have a two-step match with an Uzbek who belongs to Haplogroup P. I wonder about that person's haplogroup now. I have many other close matches with R, probably they all R2.
I checked for 0-6 matches with this haplogroup at Ysearch. At present their database has limited samples. However, following the footsteps Dr. Wells(who declared South Indians carry Haplogroup L lineage at around 50% based on, probably, Toda tribe data), I'm going to present my own intuitions/fantasies about the possible origins of this Haplogroup.
I had matches with I, I1b, J, J1, R. However, most probably all Is are I1bs, all Rs are R2s and all Js are J1s. Here goes my idea about possible origins of the man who first carried this mutation and along with him possible origins of some others.
All 20000 years and above;
1. North Africa : E , F, G, H, I, J, K, R
2. Near East(Arab lands): R2, I1b, J1
3. Central-South Asia : L, O, Q