SELENGA RIVER

river in Mongolia and east-central Russia. It is formed by the confluence of the Ider and Delger rivers, which rise in Mongolia south of Lake Hvsgl. The river thus formed flows northeast to join the Orhon River at Shbaatar; from that point it is called the Selenga River. It continues north into Russia and bends eastward to Ulan-Ude, capital of Buryatiya. From there the river flows north to Tataurovo, where it swings westward and flows across a delta into Lake Baikal. From Shbaatar to its mouth the Selenga flows down a gentle slope, giving access from Mongolia to the plains of Asiatic Russia. The Trans-Siberian Railroad follows the river's valley upstream to Ulan-Ude, where a branch continues to Shbaatar, and then up the Orhon to Ulaanbaatar, capital of Mongolia. The Selenga is 920 miles (1,480 km) long and is navigable from its mouth to beyond Shbaatar in MayOctober, when it is ice-free. Its 173,000-square-mile (448,000-square-kilometre) basin includes the Mongolian tributaries of the Orhon, Hanuy, and Egiyn and the Russian Chikoy, Khilok, Uda, Dzhida, and Temnik rivers. Karakorum, ancient capital of the Mongol empire, was situated near the upper Orhon.