The above are Y chromosomes from ancient samples in the steppe, Iran/Turan, and South Asia. The time periods are obvious. EMBA = “Early Middle Bronze Age”, MLBA = “Middle Late Bronze Age” and LBA = “Late Bronze Age.” IA = “Iron Age.” H = “Historical.” And the other periods are Neolithic or Copper Age. This is from Narasimhan et al. (click the image above for the supplements).
The Forest/Steppe samples are most from what Sintashta archaeological sites. One thing that is evident in early Indo-European pastoral people is that they seem to be highly patrilocal and patrilineal. One particular genetic lineage group of males seems to dominate different early groups. The data from Narasimhan et al. show us that:
R1a is overwhelming in the Sintashta.
R2 & L is found in pre-Indo-European Iran.
Q & N is in Sintashta too.
H1 is mostly found in South Asian populations.
You can see the distribution in modern populations on Wikipedia, but data from a paper is illustrative: