Perhaps the tombstone upon all theories of hg. R1b come from Middle East to Western Europe with agriculturalists
Frequently in the past I used the study and the path of rare haplogroups (Y and mt) to understand their origin and their pathway. I arrived in this way to my theory of an Italian Refugium and the peopling of Western Europe after the Younger Dryas and the first expansion with agriculturalists to Iberia and Central Europe. My mt K1a1b1e is a clear tool for demonstrating the origin in Italy and the diffusion to the Isles via Central Europe. Y R-L51 and R-P312/DF27- are tools for demonstrating the expansion via Iberia etc.
In appearance this paper studies the Belorusians but says much more: A. Kushniarevich et al., Uniparental Genetic Heritage of Belarusians: Encounter of Rare Middle Eastern Matrilineages with a Central European Mitochondrial DNA Pool, PLOS ONE, June 2013.
The authors, many illustrious (the Italians Achilli and Torroni and the Israelian Behar), take in consideration two very rare mt: N1a3 and N3.
Apart the fact that I don't understand why their origin is believed in Middle East (N1a3 has "the highest frequencies but a rather low diversity in Middle East" p. 4, and this shouldn't be a merit), their diffusion would demonstrate that the expansion happened after the Younger Dryas:
"It suggests that movement of populations over the West Asian space during the Pleistocene-Holocene boundary, coinciding perhaps with the end of the Younger Dryas, was more intense than in later periods, during the mid-Holocene, well after the transition of human to agriculture and largely sedentary lifestyle" (p. 6).
You know that my theory presupposes that R1b1 was in the Italian Refugium during the Younger Dryas and that its Western European subclades derive from it an not from other R1b1 present in the Caucasus or elsewhere.