Part of the old imperial family and its following fled northwards from Liu Yü and surrendered to the Toba. There they agitated for a campaign of vengeance against South China, and they were supported at the court of the Toba by many families of the gentry with landed interests in the south. Thus long-continued fighting started between Sung and Toba, concerned mainly with the domains of the deposed imperial family and its following. This fighting brought little success to south China, and about 450 it produced among the Toba an economic and social crisis that brought the wars to a temporary close. In this pause the Sung turned to the extreme south, and tried to gain influence there and in Annam. The merchant class and the gentry families of the capital who were allied with it were those chiefly interested in this expansion. About 450 began the Toba policy of shifting the central government to the region of the Yellow River, to Loyang; for this purpose the frontier had to be pushed farther south. Their great campaign brought the Toba in 450 down to the Yangtze. The Sung suffered a heavy defeat; they had to pay tribute, and the Toba annexed parts of their northern territory. The Sung emperors who followed were as impotent as their predecessors and personally much more repulsive. Nothing happened at court but drinking, licentiousness, and continual murders. From 460 onward there were a number of important risings of princes; in some of them the Toba had a hand. They hoped by supporting one or another of the pretenders to gain overlordship over the whole of the southern empire. In these struggles in the south the Hsiao family, thanks mainly to General Hsiao Tao-ch'eng, steadily gained in power, especially as the family was united by marriage with the imperial house. In 477 Hsiao Tao-ch'eng finally had the emperor killed by an accomplice, the son of a shamaness; he set a boy on the throne and made himself regent. Very soon after this the boy emperor and all the members of the imperial family were murdered, and Hsiao Tao-ch'eng created the "Southern Ch'i" dynasty (479-501). Once more the remaining followers of the deposed dynasty fled northward to the Toba, and at once fighting between Toba and the south began again.