NOMADS AND FARMERS (COMMENT). Annalisa commented here about the Yamnaya that: “Is it common for nomads to displace the settled local population? I hadn’t thought so. I was under the impression that farming technology and attitudes led to the rise of the dominant groups in continental Europe.” Annalisa is spot on. She remembers what people learned in school until very recently. Reich on page 118 summarizes the leading theory in the 1980’s that “since once densely settled farming populations were established it was difficult to imagine how other groups could gain a foothold, [Colin] Renfrew and scholars who followed him concluded that the spread of farming was probably what brought Indo-European languages to Europe.”
Reich believes that the evidence from ancient DNA that has been found in the last few years has overturned the prior theories. He also notes that “the Indo-European languages spoken today, from India in the east to the Atlantic fringe in the west, descend from a language spoken by an ancient population that used wagons.”
I should also note that, as I understand it, the farmers still play an important role in the story.