Eastern Wu
Wu (Chinese: 吳; pinyin: Wú; Middle Chinese *ŋuo < Eastern Han Chinese: *ŋuɑ), known in historiography as Eastern Wu or Sun Wu, was a dynastic state of China and one of the three major states that competed for supremacy over China in the Three Kingdoms period. It previously existed from 220 to 222 as a vassal kingdom nominally under Cao Wei, its rival state, but declared complete independence from Cao Wei in November 222. It was elevated to an empire in May 229 after its founding ruler, Sun Quan (Emperor Da), declared himself emperor. Its name was derived from the place it was based in—the Jiangnan (Yangtze River Delta) region, which was also historically known as "Wu". It was referred to as "Dong Wu" ("Eastern Wu") or "Sun Wu" by historians to distinguish it from other Chinese historical states with similar names which were also located in that region, such as the Wu state in the Spring and Autumn period and the Wuyue kingdom in the Five Dynasties and Ten Kingdoms period. It was called "Eastern Wu" because it occupied most of eastern China in the Three Kingdoms period, and "Sun Wu" because the family name of its rulers was "Sun". During its existence, Wu's capital was at Jianye (present-day Nanjing, Jiangsu), but at times it was also at Wuchang (; present-day Ezhou, Hubei). History Beginnings and founding Towards the end of the Han dynasty, Sun Ce, the eldest son of the warlord Sun Jian, and his followers borrowed troops from the warlord Yuan Shu and embarked on a series of military conquests in the Jiangdong and Wu regions between 194 and 199, seizing several territories previously occupied by warlords such as Liu Yao, Yan Baihu and Wang Lang. Sun Ce broke off relations with Yuan Shu around 196–197 after the latter declared himself emperor—an act deemed as treason against Emperor Xian, the figurehead ruler of the Han dynasty. The warlord Cao Cao, who was the de facto head of government in the Han imperial court, asked Emperor Xian to grant Sun Ce the title of "Marquis of Wu" (). Sun Ce was assassinated in the summer of 200 and was succeeded by his younger brother, Sun Quan. Sun Quan, like his elder brother, also paid nominal allegiance to Emperor Xian while maintaining autonomous rule over the Wu territories. In 208, Sun Quan allied with the warlord Liu Bei and they combined forces to defeat Cao Cao at the Battle of Red Cliffs. Sun Quan and Liu Bei maintained their alliance against Cao Cao after the battle for the next ten years or so, despite having some territorial disputes over Jing Province. In 219, Sun Quan severed ties with Liu Bei when he sent his general Lü Meng to invade Liu's territories in Jing Province. Guan Yu, who was defending Liu Bei's assets in Jing Province, was captured and executed by Sun Quan's forces. After that, the boundaries of Sun Quan's domain extended from beyond the Jiangdong region to include