Xu Shu, poet, Eastern Han dynasty

Power became frayed and decentralized near the end of the Han dynasty, with the responsibility for quelling provincial rebellions left to local warlords and their armies. One such warlord, Cao Cao, seized the Han central government in 196 a .d ., and the last of the Han emperors was deposed in 220 a .d . by Cao Cao’s son, who after the establishment of his Wei dynasty ruled most of northern China from the Wei river valley. Laws were decreed forbidding women of the royal court and eunuchs from holding strong positions of power. This period of disunion was known as the Three Kingdoms (220-265 a .d .) (as China was divided into Wei, Wu, and Shu Han Kingdoms.). In addition to the Wei dynasty to the north, a remote branch of the former Han estab­ lished the Shu dynasty in the Sichuan basin through the efforts of General Guan Yu, later a legendary military hero, and Zhuge Liang. The Wei and Shu were joined by a third focal point of power in 222 a .d ., when the kingdom of Wu was established around Nanjing in the lower Yangzi river valley. After 221 a .d . the period was marked by the competition among the Three Kingdoms. Despite the turmoil, the period did not lack for tech­ nological advances: gunpowder, the kite, and the wheelbarrow were invented, and coal was first used in heating.