Northern Asia is a region of the continent of Asia consisting only of the Asian portion of Russia. The lack of any major mountain ranges in the area allows air from the Arctic to flow unhindered down across Northern Asia, bringing a cold climate to Siberia and surrounding areas. Where the region reaches north beyond the Arctic Circle, conditions are very harsh with the summer season lasting barely one month. As a result of this, a vast majority of the population of Northern Asia live in the south of the region, though, even here, the climate is generally characterised by long, cold winters and short, mild summers. Even so, the south of Siberia has suitable conditions for agriculture, with extensive growing of wheat, barley, rye and potatoes, along with the extensive grazing of sheep and cattle.