"While a good case can be made for an expansion of Pontic-Caspian pastoralists onto the Asiatic steppe, and perhaps also into the belt of central Asian urban centres (Parpola 1988), it is still difficult to demonstrate movements from the steppe into the historical seats of the Indo-Aryans and the Iranians of Iran itself."
January 1, 1970
https://en.wikiquote.org/wiki/J._P._Mallory