I think you mean A282, not Z292. And, since Z282 is R1a1a1b1 and Z93 is R1a1a1b2, it appears that they're very closely related. Estimates I've read for the time of the division would seem to match the estimated time of the first split in the presumed IE population. And I really don't follow your logic - if eastern Europe R1a is almost all Z282 and western Asia is almost all Z93, how does that "prove" anything other than what I said about the dividing line being right around the presumed IE homeland? And the probable location of the origins of R1a don't tell us anything about where R1a1a1b was located geographically when it split, as that happened many thousands of years after R1a split from R1*. I'm certainly no geneticist, so perhaps I'm misunderstanding this, but everything the experts tell us about the subclades of R1a appears to me to suggest that there was a population on the steppes a few thousand years ago that split in half, with one group going east and another going west.