For what I've read, the indoeurpeans start popping up around the world around 2000 BCE, 3000 BCE at the earliest, but by that time cities like Uruk were already 2000 years old, heck, Jericho was 7000 years old by that time.

My point is that there were already well established cultures in all the places the indoeurpeans arrived, and yet within a few centuries they had "supplanted" those cultures and as a result there are no more Akkadians nor Summerians nor Etruscans nor a lot of other cultures, and there are no cultures that descend from them.

And I can't help but wonder how were they able to have such an impact, if it had been only the Romans whipping out other cultures I'd understand, but it wasn't just the Romans, it was the Greeks, and the Hittites, and the Persians and the Sanskrits... everywhere they went the indeorupeans kicked ass, and that's not normal, why were them so successful?