system (府兵) military system, both of which became major institutions under Sui and Tang. Under the fubing system each headquarters (府) commanded about one thousand farmer-soldiers who could be mobilized for war. In peacetime they were self-sustaining on their land allotments, and were obliged to do tours of active duty in the capital. Southern Southern Chinese dynasties, being descended from the Han and Jin, prided themselves on being the successors of the Chinese civilization and disdained the Northern dynasties, who they viewed as barbarian usurpers. Southern armies continued the military system of Buqu or hereditary soldiers from the Jin dynasty. However, the growing power of aristocratic landowners, who also provided many of the buqu, meant that the Southern dynasties were very unstable; after the fall of the Jin, four dynasties ruled in just two centuries. This is not to say that the Southern armies did not work well. Southern armies won great victories in the late 4th century, such as the battle of Fei at which an 80,000-man Jin army crushed the 300,000-man army of Former Qin, an empire founded by one of the Wu Hu tribes that had briefly unified North China. In addition, under the brilliant general Liu Yu, Chinese armies briefly reconquered much of North China. Sui–Tang In 581 AD, the Chinese Yang Jian forced the Xianbei ruler to abdicate, founding the Sui dynasty and restoring Chinese rule in the North. By 589 AD, he had unified much of China. The Sui's unification of China sparked a new golden age. During the Sui and Tang, Chinese armies, based on the Fubing system invented during the era of division, won military successes that restored the empire of the Han dynasty and reasserted Chinese power. The Tang created large contingents of powerful heavy cavalry. A key component of the success of Sui and Tang armies, just like the earlier Qin and Han armies, was the adoption of large elements of cavalry. These powerful horsemen, combined with the superior firepower of the Chinese infantry (powerful missile weapons such as recurve crossbows), made Chinese armies powerful. However, during the Tang dynasty the fubing (府兵) system began to break down. Based on state ownership of the land under the juntian system, the prosperity of the Tang dynasty meant that the state's lands were being bought up in ever increasing quantities. Consequently, the state could no longer provide land to the farmers, and