China is a vast country, varying widely in its land, its climate, its agriculture and its people. Extending across some 35 degrees of latitude, and with extreme ranges in elevation and in precipitation, it has many types of agricultural production. At one extreme are the intensively cultivated rice fields of the south. On some of these, two crops of rice are grown per year; some are drained after the rice harvest for the production of a crop of winter vegetables. At the other extreme are the grassland areas of the northern Manchurian provinces, Inner Mongolia, Kansu, Chinghai, west Szechwan, Tibet and Sinkiang, with their herds of sheep, goats, cattle, yaks and camels. In between is the so-called wheat area, north of the Chingling Mountains and extending to the edge of the grasslands.