Oxus, the classical and still common name of the Amoo Darya or Jihoon, an important river of western Asia. It has its source about 15,600 ft. above the sea, in the Sir-i-Kol (Lake Sir), or Lake Victoria, in the district of Pamir, and on the recently defined boundary between Afghanistan and eastern Turkistan; flows in a generally TV. direction, forming the northern Afghan boundary, as far as the post of Khodja Salah; then takes a N. TV. course through Bokhara and Khiva, and falls through several mouths into the sea of Aral. Its length is between 1,200 and 1,300 m. For about 300 m. of the first part of its course it is called the Panja; and in this distance it receives five important and a great number of smaller affluents, draining E. Bokhara and N. E. Afghanistan. Below the most westerly of these five affluents, the Koksha river, the main stream receives the name of Amoo Darya; and from this point to its mouth it is navigable, but flows through the almost completely desert waste of Khiva. Its delta is low and marshy, and several of its mouths are so shallow as to be impassable even for small craft. The greatest breadth of the main channel of the stream is about 3,200 ft.; its greatest depth a little more than 5 fathoms.

The valley of the river, and especially that of the upper Oxus, has long been one of the most interesting regions for geographers and ethnologists; for the latter, because of the common hypothesis which regards the region about its source as the cradle of the human race; and for the former, on account of the interesting explorations made during recent years, and the theories and discoveries with regard to the ancient and modern beds of the river. It seems conclusively established that the Oxus at one time, through a course still clearly traceable, flowed into the Caspian sea. The peculiar features of the whole Khivan region, supposed to have once formed the bed of an inland sea, add to the interest of the Oxus valley. - The Oxus has been important in political history. Alexander's eastern campaigns brought him several times to its banks; and its valley was the scene of important events in later times. Recently it has been brought prominently into discussion in connection with questions of Russian possessions in central Asia. (See Afghanistan, Bokhara, and Khiva.) Of the numerous books and papers written upon the Oxus, see especially Sir H. C. Rawlinson's "Monograph on the Oxus " (" Journal of the Royal Geographical Society," 1872), and for description Mac-Gahan's " Campaigning on the Oxus, and the Fall of Khiva" (London and New York, 1874).