Emperor Xian of Han
Cao Cao died on 15 March 220. His son and successor, Cao Pi, soon forced Emperor Xian to abdicate the throne in favour of himself, ending the Han dynasty. Cao Pi established a new state known as Cao Wei (sometimes known inaccurately as the Kingdom of Wei), and he granted Emperor Xian a noble title – Duke of Shanyang (山陽公). The former Emperor Xian died in 234 and was buried with honours befitting an emperor, using Han ceremonies, and the then emperor of Wei, Cao Rui, was one of the mourners. As Emperor Xian's crown prince was already dead, his grandson Liu Kang (劉康) inherited his dukedom, which lasted for 75 more years and two more dukes, Liu Jin (劉瑾) and Liu Qiu (劉秋), until the line was exterminated by invading Xiongnu tribes in about 309, during the Jin dynasty. This practice of an emperor conferring hereditary nobility on his predecessor, from whom he usurped the throne, was known as "er wang san ke" (二王三恪).
History of the Han dynasty
After Empress Dowager Lü's death in 180 BCE, it was alleged that the Lü clan plotted to overthrow the Liu dynasty, and Liu Xiang the King of Qi (Emperor Gaozu's grandson) rose against the Lüs. Before the central government and Qi forces engaged each other, the Lü clan was ousted from power and destroyed by a coup led by the officials Chen Ping and Zhou Bo at Chang'an. Although Liu Xiang had resisted the Lüs, he was passed over to become emperor because he had mobilized troops without permission from the central government and because his mother 's family possessed the same ambitious attitude as the Lüs. Consort Bo, the mother of Liu Heng, King of Dai, was considered to possess a noble character, so her son was chosen as successor to the throne; he is known posthumously as Emperor Wen of Han (r. 180–157 BCE).