Iranian plateau
As early as the 20th century BC, tribes came to the Iranian Plateau from the Pontic–Caspian steppe. The arrival of Iranians on the Iranian plateau forced the Elamites to relinquish one area of their empire after another and to take refuge in Elam, Khuzestan and the nearby area, which only then became coterminous with Elam. Bahman Firuzmandi say that the southern Iranians might be intermixed with the Elamite peoples living in the plateau.