We are not in a position to fix the place from which and the time when the Arian tribes entered the table-land of Iran and peopled it. That Iran was not their native country is clear from the divergence of the Arian stock from the common stem of the Indo-Europeans (IV. 4). Still less can we decide whether the Arians found an older population already settled in Iran. So far as the ancient monuments of east and west allow us to form an opinion, there exist no elements of an alien language from which we could deduce the existence of an earlier population, which the Arians conquered. Yet we cannot deny that tribes of an alien origin and character were settled on the western spurs of the mountain wall of Iran, in the north no less than in the south.[23] The foreign elements which the later forms of the language of Iran have adopted are due to the influence which the Semitic neighbours of the Arians on the west, and the dominion of the Arabs, exercised on Iran. As to the direction in which the Arians entered Iran, we can only conclude, from their close relationship to the Arians of India, that they peopled the east of Iran before the west. If the Arians of India came into the Panjab, as we assumed, soon after 2000 B.C., the Arians of Iran entered the eastern part of that country at a date certainly not later. According to the list of dynasties furnished by Berosus, the Arians about 2500 B.C. were not only settled in Iran, but already possessed the western part of the country. He represents the Medes as conquering Babylonia in 2458 B.C., and from this date down to 2224 B.C. mentions eight Median kings as ruling over Babylon (I. 241, 247).