The earliest references to Turkestān that have reached us are contained in the Indian and Iranian epics, and give some colour to the theory that the Pamirs were the birthplace of the Aryan race.[1] The ancients gave the name of _Bactria_ to the tract lying between the Oxus and the mountains of the Paropamisus.[2] The earliest mention of Bactria[3] is preserved in the inscription of Behistūn, dating back to the sixth century B.C., in which it is included in the list of the satrapies belonging to the Persian Empire of Darius II. Cyrus I. subdued this country, and, according to Ctesias,[4] Bactria was the first of his conquests in Eastern Asia. The founder of the Persian Empire carried his arms as far as the Jaxartes (or Sīhūn), on the other side of which roamed the Massagetæ (B.C. 550), and near it he built a city called Cyropolis.[5] The annexation of Bactria involved that of Margiana, Khorazmia,[6] and Soghdiana. From Greek sources we learn that under the rule of Darius Hystaspes (B.C. 521–492) these districts were reckoned among the Persian satrapies; although the authority of the Achæmenians was probably but slight there. It is not unlikely that all the eastern countries mentioned in the oldest Darius inscriptions as “subdued,” or “rebellious,” had already belonged to Cyrus, and that he ruled over Khorazmia and Soghdiana.[7] The Persian monarchy finally fell before the overwhelming might and genius of Alexander of Macedon. In the space of four years (B.C. 334–331) he carried his victorious arms from the eastern shores of the Mediterranean to Persepolis, overthrowing Darius II. at Issus in B.C. 333, and again at Gaugamela[8] in B.C. 331. The latter defeat was the deathblow of the Persian monarchy. Darius fled in an easterly direction, accompanied by a still considerable army, determined if possible to enter Bactria. Alexander took and plundered Persepolis and Pasargadæ, the cradle of the Persian dynasty, and then set out in pursuit of Darius, who had reached Ecbatana, the capital of Media. But at this crisis Bessus, the governor of Bactria and commander of the contingent of that province, in conjunction with other Persian nobles, seized on the person of the king and laid him in chains. Their design was to conciliate Alexander, should he overtake them, by giving up Darius alive; while in the event of their escaping, they proposed to murder the prisoner, usurp his crown, and begin a new war.