... that Proto-European language shared a common lineage back to India from the Aryan peoples.
That common lineage (allegedly) was the Caspian Steppe, near the Caucasus mountains (hence 'Caucasian' race). It's all mostly BS. The origins of these languages and peoples (and any connecting links) are not well understood yet, there's just not enough data. Even the most well accepted 'hypotheses' are full of holes.
By the way, let's not malign Nietzsche by handing over his "Übermensch" term to this 'aryan' nonsense. Nietzsche would have died of rage if he knew how the Nazis hijacked this term.