The inscriptions of the Assyrians have already informed us that no dominion of Assyria over Eastern Iran existed in the earliest period of the kingdom; on the contrary, even when her power was at the highest Assyria could only carry on temporary excursions into that region. The western part of the country was first trodden by the armies of Shalmanesar II.; his inscriptions mention tribute of the Medes, and from the inscriptions of his successors it is distinctly clear that only the nations of Western Iran were tributary dependants of the kings of Asshur from the period of Tiglath Pilesar, _i.e._ from the middle of the eighth century B.C., till the period of Phraortes and Cyaxares of Media, _i.e._ till the middle of the seventh century B.C.[28] The conquests of Cyrus, who overthrew the power of the Medes, founded the Persian empire, and extended it to the east, would give us more accurate information about Eastern Iran if connected accounts of these were in existence. Herodotus contents himself with stating that Cyrus, after subjugating the Lydians, determined to march against the Bactrians and Sacæ. He conquered all the nations of Upper Asia, one after the other, without omitting any.[29] Ctesias relates that the Bactrians after a doubtful battle submitted voluntarily to Cyrus. According to the account of Xenophon, the Hyrcanians, Cadusians, and Sacæ joined Cyrus, and in the fragments of Nicolaus also the Hyrcanians, Parthians, and "the other nations" passed over to Cyrus immediately after the conquest of the Medes. However this may be, there is no doubt that the east of Iran was subject to Cyrus. He marched through the land of the Arachoti, entered into relations with the Ariaçpas (p. 8), and subjugated the Gandarians on the south of the Cabul. He is also said to have imposed tribute on the Açvakas to the north of the river (IV. 384). The Sogdiani, in any case, were his vassals. On a stream which flows into the Jaxartes he built a fortress called by his own name, known to the Greeks as Cyresbata (_ultima Cyra_, or with others Cyropolis), _i.e._ the furthest Cyrus. The walls and citadels were strong and spacious, and in the neighbourhood were six other citadels.[30] The value placed by Cyrus on the regions of Eastern Iran is not only clear from these fortresses, but may be deduced from the statement that his second son Bardya, whom the Greeks call Smerdis, was intrusted with the government of Bactria, if indeed the statement is genuine.[31]