Siberia is an extensive geographical region, and by the broadest definition is also known as North Asia. Siberia has been historically part of Russia since the seventeenth century.  The territory of Siberia extends eastwards from the Ural Mountains to the watershed between the Pacific and Arctic drainage basins. Siberia stretches southwards from the Arctic Ocean to the hills of north-central Kazakhstan and to the national borders of Mongolia and China. Siberia accounts for 77% of Russia's land area (13.1 million square kilometres), but is home to just 27% (40 million people) of the country's population.