In the early 1850s, the Chinese living in the Yellow River (Huang Ho) valley suffered famine because of repeated flooding of the river; many of them joined outlaw bands, called nien, which had been plundering the provinces of Anhwei, honan, and Shantung during the first half of the century. While the Manchu (Ch'ing, Quing) government was preoccupied with the Taiping Rebellion in the south, the Nien bands formed armies, notably under the leadership of Chang Lohsing (d. 1863), and fortified their villages and took advantage of the mobility of their strong cavalry to harass and evade imperial troops seeking to crush them. The soon controlled a large area in north China that was virtually independent of the rest of the country. However, their movement lacked strong direction after Chang Lo-hsing was killed, and the Nien were unable to coordinate their actions with the Taiping rebels in the south. Imperialforces led successively by Generals Seng-ko-linch'in (d. 1865), Tseng Kuo-fan (1811-72), and Li Huang-chang (1823-1901) surrounded the Nien fortresses, starved them into submission, and sacked their strongholds. By 1868, the rebels were defeated, and the emperor's forces were again in command of their area.