If we come back in far past we find our "lineages" drowned into older more common lineages, so eve if Y-R1a and R1b were from East Asia (which is not exactly 'East Eurasia' in my mouth or pen), I would not care too much. I think they developped between South Central Eurasia and North Central Eurasia. For R1a I lack sufficient knowledge to date (history of subclades). Concerning R1b-M269 I suppose it developped in Eastern Europe rather than South the Caucasus, but who knows with certainty? (It's not Maciamo's theory)
That said, this forum is for people who try to know more, not for people who want or want not something, even if when accurate answers are obtained, we would prefer they would be of our taste. But reality is not myth or dream.