Syr Darya (Persian Sihun; ancient Jaxartes or Yaxartes), river, Central Asia. One of the major rivers of the region, it is formed by the junction of the Naryn River and the Qoradaryo in Fergana Valley, Uzbekistan. It flows generally west through Uzbekistan, Tajikistan, and Kazakhstan into the Small Aral Sea, which separated from the Large Aral Sea in 1988. Since the 1950s the river has been heavily tapped for irrigation, which has greatly reduced its water level and the amount of water reaching the Aral. From 1974 to 1986 almost no water reached the Aral from the river. As a result, and due to the fact that inflows from the Amu Darya have also drastically diminished in recent decades, the volume of the Aral Sea dropped by about 76 percent between 1960 and 1995. The river is 2,200 km (1,370 mi) long.