Economic Expansion. While the Song dynasty (960- 1279) was characterized by financial problems and military weakness, it also experienced an economic expansion so great that it was referred to as the "commercial revolution" by scholars. The economic upturn was chiefly propelled by improved agricultural technologies; the use of the abacus, gunpowder, and new printing techniques; the growth of domestic and foreign trade; and the development of a money economy.

Technological Development. A great increase in agricultural productivity occurred during the Song era. In southern China the double cropping of rice was made possible by the introduction of a new strain of rice, which matured more quickly than local plants, from Champa in southern Vietnam. Several major water-control projects were undertaken that significantly improved the irrigation of rice paddy fields. In addition, more commercialized crops were introduced into farming...