Siberia (; Russian: Сибирь, tr. Sibír', IPA: [sʲɪˈbʲirʲ] (listen)) is an extensive geographical region spanning much of Eurasia and Northern Asia. Siberia has been part of modern Russia since the latter half of the 16th century.The territory of Siberia extends eastwards from the Ural Mountains to the watershed between the Pacific and Arctic drainage basins. The river Yenisey 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 only 23% of the country's population (approximately 33 million people). 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 by 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 governments as a place for prisons, labor camps, and internal exile. Slavic influences, especially Russian, are strong in the southwestern and central part of the region, due to its high Russian population which began to settle the area in the 18th century.