Siberia's administrative units are the Altai, Buryat, Khakass, and Tuva republics, the Altai, Krasnoyarsk, and Transbaykal territories, and the Omsk, Novosibirsk, Tomsk, Kemerovo, and Irkutsk regions. Lying off Siberia in the Arctic Ocean are the New Siberian Islands, the Severnaya Zemlya Archipelago, and other islands.
Siberia may be divided, from north to south, into the zones of vegetation that run across Russia—the tundra (extending c.200 mi/320 km inland along the entire Arctic coast), the taiga, the mixed forest belt, and the steppe zone. Forests occupy about 40% of Siberia's land. Siberia is drained, from south to north, by the Ob, Yenisei, and Lena rivers (and their tributaries), which also provide the only means of longitudinal transportation. These rivers empty northward into the Arctic Ocean. East-west transportation depends largely on the Trans-Siberian RR (which follows the steppe belt), on the Baykal-Amur Mainline (BAM), and to an increasing extent on the Arctic sea route.
Siberia is conventionally subdivided into the following four geomorphological areas: the West Siberian lowland; the Central Siberian plateaus, or uplands; the mountains of the south; and the northeast Siberian mountain systems. The lowland occupies the western third of Siberia; it stretches from the Urals to the Yenisei and is mainly a low-lying, often marshy, plain. It is drained by the Ob and Irtysh rivers, which are ice-free and navigable for about half the year. Situated far from vulnerable frontiers, SW Siberia contains about 60% of Siberia's population, major industrial complexes, and such important cities as Novosibirsk (the leading industrial and scientific research center of Siberia), Omsk, Tomsk, Tobolsk, Barnaul, and Novokuznetsk.
The wooded steppe and fertile black earth of W Siberia favor agriculture and, especially in the Baraba Steppe, dairying. Wheat is the principal crop; rye, oats, potatoes, sunflowers, flax, and sugar beets are also important. Butter is the major dairy product. The Kuznetsk Basin, in W Siberia, is one of the world's richest coal regions and also has modest iron deposits. It forms the basis for the region's iron, steel, and heavy metallurgical industries. Rich oil and natural-gas fields have been exploited in the West Siberian lowlands, from which a network of pipelines now serves European Russia and the E European republics.
E Siberia, which is drained by the Lena, extends from the Yenisei to a huge mountain chain, an offshoot of the mountains of Central Asia, comprising (from southwest to northeast) the Yablonovy, Stanovoy, Verkhoyansk, Kolyma, and Cherskogo ranges. In the center of E Siberia rise the Central Siberian uplands, which are separated from the northeastern mountains by the plateaus along the Vitim and Aldan rivers. South of the uplands lies Lake Baykal, the world's deepest lake, surrounded by mountains. E Siberia's important cities include Krasnoyarsk, Irkutsk, Ulan-Ude, Cheremkhovo, Yakutsk, and Chita; but most of the region is sparsely populated because of the extreme rigors of the climate and the difficulties of communication. Verkhoyansk, the coldest permanently inhabited settlement on earth (-56°F/-49°C on average in winter) has summer hot spells where the temperature rises above 90°F (32°C).
E Siberia is Russia's leading producer of gold, diamonds, mica, and aluminum, and there are large reserves of iron ore, coal, oil, gas, graphite, and nonferrous precious metals. Exploitation of the region's rich waterpower resources began in the mid-1950s, and there are four giant hydroelectric power stations on the Angara River between Irkutsk and Lake Baykal. Forestry, like mining, is a major economic activity in E Siberia. Agriculture (wheat and oats) is practiced in the south, and animal husbandry is prevalent among the indigenous Siberian peoples. Reindeer breeding, fishing, sealing, hunting, and fur processing are important occupations in the Arctic north.