Iranian plateau
Records become more tangible with the rise of the Neo-Assyrian Empire and its records of incursions from the 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. By the mid-first millennium BC, Medes, Persians, and Parthians populated the Iranian plateau. Until the rise of the Medes, they all remained under Assyrian domination, like the rest of the Near East. In the first half of the first millennium BC, parts of what is now Iranian Azerbaijan were incorporated into Urartu.