Below is a plot for a K = 17 ADMIXTURE analysis that includes samples from across prehistoric Eurasia.
The correspondences between the colors and the components are as follows:
Bushman and Pygmy
European hunter-gatherer Caucasoid
Northern European Caucasoid
Southern European Caucasoid
Northern Middle Eastern Caucasoid
Southern Middle Eastern Caucasoid
Taiwanese aborigine Mongoloid
Itelmen and Koryak
In this analysis the prehistoric R1b and R1a populations of Europe and Northern Asia show little to none of the Middle Eastern or South Asian components that they appear to have so much of in other ADMIXTURE analyses.
David Reich and his associates at one time made the absurd claim that Northern Europeans have a large amount of admixture from an Amerindian-like population, and they later claimed that the people of the Pit Grave culture had a large amount of admixture from an Armenian-like population. But just as the appearance of Amerindian-like admixture in Northern Europeans was an illusion that resulted from Northern-European-like admixture in Amerindians, the appearance of Middle Eastern or South Asian admixture in northern R1b and R1a populations like the Pit Grave population is an illusion resulting from admixture from R1b and R1a northerners in the populations of the Middle East and South Asia.