Strictly speaking, Cao Cao was not from the Three Kingdoms period, but from the late Eastern Han Dynasty. From a historical perspective, most people generally believe that the Three Kingdoms period should be from 220 to 280. In 220, Cao Cao passed away, and Cao Pi inherited Cao Cao's official title. In the same year, Cao Pi deposed the Han Dynasty and became emperor, proclaimed himself emperor, and founded the country with the name Wei. It is called Cao Wei in history.
From this point of view, after Cao Pi proclaimed himself emperor in 220, the history of the Three Kingdoms officially began. By 229, when Sun Quan proclaimed himself emperor, the Three Kingdoms were officially established. By 280, the Western Jin Dynasty destroyed Dongwu and completed the unification. At this point, the Three Kingdoms period ended. Before Cao Pi became emperor, Cao Cao was no longer alive, so Cao Cao belonged to the late Eastern Han Dynasty, not the Three Kingdoms period.
It is said that Cao Cao was from the Three Kingdoms period because he created the entire Wei State. He was the founder of Wei State and the founder of Wei, Emperor Wu of Wei. In the later period, Cao Cao was granted the title of Duke of Wei and King of Wei by the Han Dynasty, which laid the political foundation for Cao Pi to stand on his own behalf on behalf of the Han Dynasty. When Cao Cao was still alive, he implemented the strategy of "obeying the emperor's orders and disobeying the ministers", unified northern China, and also It laid the military foundation for Cao Pi.
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Cao Cao's old age as a warrior:
After Sun Quan captured Guan Yu and captured Jingzhou, Cao Cao represented Sun Quan as General of Hussars and Mu of Jingzhou. Sun Quan sent envoys to pay tribute to Cao Cao, and persuaded Cao Cao to replace the Han Dynasty and claim to be the emperor of the Wei Dynasty. Cao Cao showed Sun Quan's letter to all the officials at home and abroad, saying: "My son wants to sit on top of my fire!" Cao Cao's officials took the opportunity to persuade Cao Cao to come forward.
Cao Cao himself did not want to depose Emperor Xian and establish himself. He said: "If fate is mine, I will be King Wen of Zhou." In the first month of the twenty-fifth year of Jian'an (220), Cao Cao returned to Luoyang. That month, he died of illness in Luoyang at the age of sixty-six, and his posthumous title was King Wu. Before his death, he left a "posthumous order".
According to Cao Cao's will, he was buried in Gaoling in the western suburbs of Yecheng (now Linzhang County, Handan, Hebei) on February 21st (April 11th). In October, King Cao Pi of Wei replaced the Han Dynasty and proclaimed himself emperor. His country was named Wei. He followed Cao Cao as Emperor Wu and his temple was named Taizu.
Reference: Baidu Encyclopedia-Cao Cao