Jaxartes, now called Sihun, or Syr-Daria (both syr and daria mean 'river'), a river of western Asia, which rises at an altitude of 12,000 feet, 30 miles S. of Lake Issik-kul, in the Tian-Shan Mountains. It is at first called the Jaak-tash, then the Taragai, and under the name of the Naryn it descends, through a wild narrow gorge, to the level of 6800 feet at Fort Narynsk, and flowing W. and SW. A little west of Khojend it breaks through another gorge; then turns suddenly to the north-west, and, retaining that direction for 850 navigable miles, finds its way into the Sea of Aral by a delta with three mouths. Its total length is 1500 miles ; area of its drainage basin, 320,000 sq. m. Five centuries ago the Syr-Daria used to send off a south-western branch at Perovsk, which flowed into the Sea of Aral on its south-east side, not far from the mouth of the Amu-Daria. This branch is now lost in the sand. The Syr-Daria is the Nile of Turkestan. The people fertilise their valleys by its water, carried off in irrigation channels.