The Genetic Origin of the Indo-Europeans

[pelop]

My guess is that their mobility and their consequent ability to control routeways and networks was the key advantage over groups who used the traditional static subsistence model of small villages that stretched back to the Neolithic. They likely had the only languages that could be heard across vast ranges (even if in low numbers) while each region with a static farming model might have had its own dialect with mutual intelligibility problematic. Also there is a natural tendency in small level societies for more mobile outgroup to have control of trade route and have the military upper hand over small scale static groups. It might have started as a symbiotic thing of mutual advantage but with the more mobile groups morphing into the rulers.  

I don't think this idea of Anatolia in 3000 BC being stuck in an early Neolithic type of social organisation is very accurate. In fact we know that migrants from Anatolia, carrying Iran_N-related admixture, were migrating to the Aegean islands and mainland Greece, probably already by the Late Neolithic period. See Mathieson et al 2018, Clemente et al 2021, Skourtanioti et al 2023.