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.
Gengshi Emperor
By this point, many other rebel leaders had become jealous of Liu Yan's capabilities, and while a good number of their men admired Liu Yan and wanted him to become the emperor of a restored Han dynasty, they had other ideas. They found another local rebel leader, Liu Xuan, a third cousin of Liu Yan, who was claiming the title of General Gengshi (更始將軍) at the time and who was considered a weak personality, and requested that he be made emperor. Liu Yan initially opposed this move and instead suggested that Liu Xuan carry the title "King of Han" first (echoing the founder of the Han dynasty, Emperor Gaozu). The other rebel leaders refused, and in early 23, Liu Xuan was proclaimed emperor. Liu Yan became prime minister.