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).
Chu–Han Contention
The Chu–Han Contention (206–202 BC) was an interregnum between the Qin dynasty and the Han dynasty in Chinese history. Following the collapse of the Qin dynasty in 206 BC, Xiang Yu split the former Qin Empire into the Eighteen Kingdoms. Two major contending powers emerged, Western Chu and Han, which engaged in a struggle for supremacy over China. Western Chu was led by Xiang Yu, while the Han leader was Liu Bang. Several minor kings also warred, but these were largely independent of the main conflict between Western Chu and Han. The war ended in 202 BC with total victory for Han, with Liu Bang soon proclaiming himself first emperor of the Han dynasty.