Naryn (nərĬn´), river, c.450 mi (720 km) long, rising in several branches in the Tian Shan mountain system, SW Kyrgyzstan and SE Uzbekistan. The longest river in Kyrgyzstan, it flows generally W through the Fergana Valley where it joins with the Kara Darya to form the Syr Darya. The upper course is used for producing hydroelectricity; the lower course for irrigating a cotton-growing area. The city of Naryn (1997 est. pop. 46,400), SW Kyrgyzstan, on the upper course of the river, at an altitude of 6,610 ft (2,015 m), is the center of a wheat-growing and sheep-grazing district.