List of emperors of the Han dynasty
The Han dynasty was founded by the peasant rebel leader (Liu Bang), known posthumously as Emperor Gao ("r". 202 –195 BC) or Gaodi. The longest reigning emperor of the dynasty was Emperor Wu ("r". 141–87 BC), or Wudi, who reigned for 54 years. The dynasty was briefly interrupted by the Xin dynasty of the former regent Wang Mang, but he was overthrown in 23 AD and the Han dynasty was reestablished by Liu Xiu, known posthumously as Emperor Guangwu (r. 25–57 AD), or Guangwu Di. The last Han emperor, Emperor Xian ("r". 189–220 AD), was a puppet monarch of Chancellor Cao Cao (155–220 AD), who dominated the court and was made King of Wei. In 220 AD, Cao's son Pi usurped the throne as Emperor Wen of Wei ("r". 220–226 AD) and ended the Han dynasty.
Cao Zizheng
In 220, Cao Zizheng's half-brother Cao Pi became the first emperor of the Cao Wei state after usurping the throne from Emperor Xian, the last emperor of the Han dynasty. The following year, he honoured Cao Zizheng with the posthumous title "Duke Dai of Mei" (郿戴公), and ordered Cao Fan (曹範), a son of Cao Ju, to be Cao Zizheng's heir. In 222, Cao Pi enfeoffed Cao Fan as the Marquis of Pingshi (平氏侯), but changed his title to Marquis of Chengwu (成武侯) in the following year. In 229, Cao Pi's successor, Cao Rui, promoted Cao Fan from a marquis to a duke. Cao Fan died in 235 without a son to succeed him, and was posthumously honoured as "Duke Dao" (悼公). In 236, Cao Rui ordered Cao Chan (曹闡), Cao Fan's younger brother, to be Cao Fan's heir. Cao Chan thus became the new Duke of Mei (郿公). Throughout the reigns of the subsequent Wei emperors, the number of taxable households in Cao Chan's dukedom increased until it reached 1,800.