The European R1b and African split 17,000 years ago, it looks like T arrived along the Natufian migration and then followed by R1b shortly after, from the papers I've read.It went opposite direction too. From Africa to Europe. R1b-V88 cattle herders from the Near East managed to get to Western Europe via North Africa, probably crossing at Gibraltar. The oldest known R1b-V88 sample in Europe is a 7,100 year-old from the Catalan Pyrenees tested by Haak et al. 2015 and whose autosomal DNA matched that of other Neolithic farmers, without a trace of Steppe ancestry!