The territory of Siberia extends eastwards from the Ural Mountains to the watershed between the Pacific and Arcticdrainage basins. The Yenisei River conditionally divides Siberia into two parts, Western and Eastern. Siberia stretches southwards from the Arctic Ocean to the hills of north-central Kazakhstan and to the national borders of Mongolia and China. With an area of 13.1 million square kilometres (5,100,000 sq mi), Siberia accounts for 77% of Russia's land area, but it is home to approximately 36 million people—27% of the country's population. This is equivalent to an average population density of about 3 inhabitants per square kilometre (7.8/sq mi) (approximately equal to that of Australia), making Siberia one of the most sparsely populated regions on Earth. If it were a country by itself, it would still be the largest country in area, but in population it would be the world's 35th-largest and Asia's 14th-largest.
Worldwide, Siberia is well known primarily for its long, harsh winters, with a January average of −25 °C (−13 °F), as well as its extensive history of use by Russian and Soviet administrations as a place for prisons, labor camps, and exile.
The origin of the name is unknown. Some sources say that "Siberia" originates from the Siberian Tatar word for "sleeping land" (Sib Ir). Another account sees the name as the ancient tribal ethnonym of the
Sirtya [ru] (also "Syopyr" (sʲɵpᵻr)), an ethnic group which spoke a Paleosiberian language. The Sirtya people were later assimilated into the Siberian Tatars.
The modern usage of the name was recorded in the Russian language after the Empire's conquest of the Siberian Khanate. A further variant claims that the region was named after the Xibe people. The Polish historian Chycliczkowski has proposed that the name derives from the proto-Slavic word for "north" (север, sever), but Anatole Baikaloff has dismissed this explanation. He said that the neighbouring Chinese, Turks, and Mongolians, who have similar names for the region, would not have known Russian. He suggests that the name might be a combination of two words with Turkic origin, "su" (water) and "bir" (wild land).