Thinking further on the table from Wikipedia I linked to above …
If Jeanson’s “R1b’s migration from Asia into Europe” in the last two millenia were true, we would expect to see the main R1b hotspots where such migrations/invasions occured: Huns into Eastern and Central Europe, Turks into the Balkans, Mongols into Russia and Ukraine. Although we do see hotspots for the Turkic Bashkirs (86%) and Chuvash (79%), we see low measures for Turks (8-16%), Greeks (11-17%), Russians (3-8%), and hotspots in the far west of Europe, well away from these migrations: Basques (93%, with lower but still high levels in other Iberian populations), Welsh (89%, again with lower but still high levels in Irish, Scots & Orcadians), and moderately high levels in the English and the Low Countries (50-63%). This distribution simply does not fit Jeanson’s thesis.
Rather, it would appear to support a thesis of R1b traveling to some areas with the Celtic migrations (starting in the 6th Century BCE, but from the ‘Hallstatt’ territory in Central Europe, not Central Asia – the migration from Central Asia must have happened well before this), and probably dating back to neolithic times with the Basques.
This map perhaps describes this more visually:
