Shaanxi (shänˈshēˈ) [key] or Shensi shĕnˈsēˈ [west of the mountain passes], province (2010 pop. 37,327,378), c.76,000 sq mi (196,840 sq km), N central China. Xi'an is the capital. From north to south Shaanxi has four main regions—the loess plateau, fertile but dry; the Wei River valley, rich agriculturally and the center of population; the Qinling divide, the highest range of the province; and the upper Han River valley. The valleys of the Wei and Han rivers and newly irrigated areas in the northwest are the main farming regions. Extensive reforestation, terracing, and irrigation have reclaimed much eroded land and increased agricultural output. Wheat, millet, cotton, soybeans, and corn are the chief crops. Rice, tea, and tung oil are produced in the south, and fruit orchards are cultivated in the upland areas. Livestock (notably sheep) are raised. Shaanxi has rich coal and iron deposits. Oil is extracted at Yanchang, just E of Yan-an, and salt is obtained from lakes. China's main east-west railroad traverses Shaanxi through the Wei valley. A branch line links the west with Chengdu in Sichuan prov. A highway ties the Wei valley to the northwest. Important population centers are Xi'an, Baoji, Tongchuan, Xianyang, and Yan'an. Since the 1960s, Shaanxi has developed industrially; cotton, once sent to Shanghai for processing, is spun and woven in the province. Shaanxi's main industrial city is Xi'an, which has a variety of heavy and light industries. Shaanxi, especially the Wei River valley, was one of the early major political and cultural centers of N China. The founders of the Chou, Ch'in, and T'ang dynasties built their power there, and the Manchus gave the province its present boundaries. There was a widespread Muslim rebellion in Shaanxi in the 1860s. In 1935 the Communist army came to Yan'an in Shaanxi on its "long march," and from 1935 until the assumption of power in 1949, Shaanxi was the seat of the Chinese Communists.