During the period of disunion (220-589), the mass of sedentary agriculturalists in north China was ruled by an elite military-political class of nomads and a rising class of Chinese who had to a considerable degree adopted the culture of the nomadic conquerors. It was this new class that led the wars of conquest in the late sixth century that resulted in the reunification of the Chinese world. The resulting Sui (581-618) and early Tang (618-907) dynasties reflected the combination of the two cultures, with their military forces composed of a mix of massed hereditary soldiers who were expected to be selfsupporting and an elite cavalry force as their main offensive weapon.
The growing economic and cultural importance of the south, and the sheer mass of people there, led to the cavalry arm of the military becoming more and more foreign in nature and less and less integrated into the Tang sociopolitical system. By the late Tang, the nomadic cavalry was a fully hired force, but the succeeding Song dynasty, soon after its founding in the tenth century, lacked much of a cavalry force at all. This put the Song at a distinct disadvantage in its military encounters with its northern adversaries, particularly the Khitans and Jurchens.
The trend away from synthesis of Chinese and nomadic elements in Chinese armies also contributed to the decline of the great aristocratic families who had been in the forefront of that synthesis. When their power was destroyed in the chaos of the end of the Tang and the Five Dynasties period, the stage was set for a decisive civilianization of Chinese society under the Song, who were acutely conscious of the role of overpowerful military governors in the previous dynasty’s fall. But the Song army proved incapable of holding northern China, and it would be a newly reconstructed Song army and state that would face Jurchen and Mongol threats after 1128.
Forage, Paul C. “The Sino-Tangut War of 1081-1085.” Journal of Asian History, 25 (1991): 1-28. An especially good article demonstrating the tremendous logistic abilities of the Song military.
Graff, David A. Medieval Chinese Warfare, 300-900. London and New York: Routledge, 2002. An excellent survey of the Sui and Tang military, utilizing a tremendous amount of research in the primary sources.
Graff, David A., and Robin Higham, eds. A Military History of China. Boulder: Westview Press, 2001. A narrative history focusing on military institutions and strategy.
Haeger, John, ed. Crisis and Prosperity in Sung China. Tucson: University of Arizona Press, 1975. Includes several chapters covering Song dealings with the nomadic kingdoms in north China.
Pulleyblank, E. G. The Background to the Rebellion of An Lushan. London: Oxford University Press, 1955. Although primarily focused on the politics behind the great rebellion of the Tang dynasty, also contains much information on the organization of the early Tang military.
Rossabi, Morris, ed. China Among Equals. Berkeley: University of California Press, 1983. While not concerned primarily with military matters, includes several chapters dealing with Tang and especially Song diplomatic and strategic concerns.
Van de Ven, Hans, ed. Warfare in Chinese History. Leiden: Brill, 2000. Includes several analytical chapters concerning China’s military relations with its northern neighbors.
Wright, Arthur. The Sui Dynasty. New York: Knopf, 1978. Not only the best survey of the history of this dynasty, but a font of information on Sui campaigns against Korea.
Wright, Arthur, and Denis Twitchett, eds. Cambridge History of China. Vol. 3: Sui and T’ang China 589-906. Cambridge: Cambridge University Press, 1979. A good general survey of these two dynasties, with a great deal of specific information on Chinese military institutions and their evolution.