During the Three Kingdoms period, Cao Cao led the army to fight for Hanzhong, and a battle around the "chicken ribs" password strangled the lives of Yang Xiu's smart people, and at the same time showed the embarrassing situation in Hanzhong: "Abandon it like a pity, and you will get nothing from eating", and finally Cao's army had to retreat. However, the examination of history reveals the actual situation in Hanzhong, which is not as embarrassing as it was when it was abandoned.
In 215 AD, Sima Yi advocated that Cao Cao take advantage of the victory to go south to conquer Shu, firmly believing that the loss of Hanzhong was the opportunity for Shu Han: "Liu Bei captured Liu Zhang by deception, and the Shu people fought for Jiangling without attaching it, and this opportunity could not be lost." Sima Yi had a clear understanding of the strategic significance of Hanzhong, and advocated that Cao Cao should seize the opportunity to cause Shu to collapse in a tremor. And Liu Ye has already had a similar prophecy, pointing out that Shu Han will inevitably become a worry in the future. However, Cao Cao did not heed these suggestions, insisting that Shu was "delirious" and not worth the military effort. This opportunity was missed, and the consequences were unimaginable.
In December of the twentieth year of Jian'an, Cao Cao personally led the army from Nanzheng, the capital of Hanzhong, to return to the division, and Xiahou Yuan stayed behind. However, Xiahou Yuan was finally defeated by Shu Han's full force, and he himself was killed by Huang Zhong. Although Cao Cao personally led his army to Hanzhong again, he still failed to occupy it for a long time. Compared with the abandonment of Hanzhong, the Cao Wei regime shrank the defense line to the Guanlong area, easily solved the problem of military food supply, and at the same time used this place as a solid defense line, blocking the road of the Shu Han regime's outreach, making Hanzhong a "lonely" place.
Reflecting on history, if Cao Cao had not given up Hanzhong at the beginning, but had fought with the Shu army here, Cao Wei would have consumed a lot of resources in the Qishan Mountain Road, which would eventually lead to the exhaustion of national strength and low morale. Looking at the entire historical pattern, the abandonment of Hanzhong created a more favorable strategic situation for Cao Wei.