Kings of the Han dynasty
The kings from other dynasties (, "yìxìng wáng") were mostly remnants of the rebellion against the Qin dynasty. Following the Dazexiang Uprising, many noblemen rose in rebellion. Heirs, pretenders, and warlords called themselves "kings" and claimed sovereignty as continuations of the six states previously suppressed by Qin. Among these, Chu was the most powerful. However, its rightful ruler Huai II was assassinated on the orders of the warlord Xiang Yu and the 18 Kingdoms Xiang had formed rose in rebellion against him. Liu Bang, king of Han, ultimately defeated Chu and established the new Han dynasty. The kings who had sided with him were then permitted to maintain their titles and lands. A few other kingdoms were also formed by Liu Bang for generals and favorites.
Emperor Gaozu of Han
After establishing the Han dynasty, Emperor Gaozu appointed princes and vassal kings to help him govern the Han Empire and gave each of them a piece of land. There were seven vassal kings who were not related to the imperial clan: Zang Tu, the King of Yan; Hán Xin, the King of Hán; Han Xin, the King of Chu; Peng Yue, the King of Liang; Ying Bu, the King of Huainan; Zhang Er, the King of Zhao; Wu Rui, the King of Changsha. However, later, the emperor became worried that the vassal kings might rebel against him because they after all had no blood relations with him. Han Xin and Peng Yue were (falsely) accused of treason, arrested and executed along with their families. Ying Bu and Zang Tu rebelled against him but were defeated and killed. Only Wu Rui and Zhang Er were left.