Wu (Chinese: ?; pinyin: Wú; Middle Chinese *nuo < Eastern Han Chinese: *nu?), 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 during the Three Kingdoms period. It previously existed from 220 to 222 AD as a vassal kingdom nominally under its rival state Cao Wei but declared complete independence in November 222 AD. It was elevated to an empire in May 229 AD after its founding ruler Sun Quan (Emperor Da) declared himself emperor.