What is the historical significance of Hanzhong in the history of the Three Kingdoms?

Hanzhong mentioned in Romance of the Three Kingdoms and History of the Three Kingdoms refers to Hanzhong in Shaanxi Province, which is located at the southern foot of Qinling Mountain, the west side of Daba Mountain, the east side of the northern end of Qinghai-Tibet Plateau and the southeast corner of Taibai Mountain. Named after Hanshui River in China. Its geographical location is mainly North Qinling and South Daba Mountain. When you leave Dingjun Mountain in the west, the only way to enter Hanzhong is through Yangpingguan. Yangpingguan is a mountain to the west and the Han River to the east. Crossing the Han River is the Daba Mountain area, so it belongs to the geographical position that ten thousand people can't force, and one person guards it. This is introduced in the central science and education channel "Exploration of the Source of the Han River". It is called Hanzhong. From the summer solstice to the Western Zhou Dynasty, there appeared a praise country in China. It belongs to Liangzhou and Yongzhou successively. During the Spring and Autumn Period and the Warring States Period, the territory was Nanzheng, which belonged to Bashu and Qin successively. In 3 12 BC, Hanzhong county was established in Qin dynasty, which was one of the 36 counties in the early Qin dynasty. Nanzheng (now Hanzhong City, Shaanxi Province) was established at the beginning of the county administration, and moved to Xicheng (Zhongdutai on the north bank of Hanjiang River, Ankang City, Shaanxi Province) at the beginning of the Western Han Dynasty. From the first year of Jianwu in the Eastern Han Dynasty to the sixth year (25-30 years), the county government moved to Nanzheng (now Hanzhong City). At the end of the Eastern Han Dynasty, Zhang Lu was divided into Hanzhong and changed to Hanning County; In the 20th year of Jian 'an (2 15), Cao Cao conquered Zhang Lu and changed it to Hanzhong County. In the 24th year of Jian 'an (2 19), Liu Bei still established Hanzhong County according to Hanzhong. In the fourth year of Wei Jingyuan in the Three Kingdoms (263), Wei destroyed Shu and divided it into Liang and Yi States. Liangzhou leads eight counties and governs Nanzheng. In the tenth year of Jin Taikang (289), it was changed to Han State, which was soon abolished. During the Northern and Southern Dynasties, Hanzhong belonged to Liu Song, Xiao Qi, Northern Wei, Xiao Liang, Western Wei and Northern Zhou. Liangzhou, Xingzhou (now Lueyang County) and Yangzhou (now Xixiang County) are established in the territory, and Qin Zhou and more than 70 overseas Chinese counties have settled. At the beginning of Sui Dynasty, Liang, Xing and Yangzhou were still in China, and later changed to Hanchuan County, Shunzheng County and Yangchuan County. In the Tang Dynasty, Liangzhou was set as the Governor's House, which was later changed to the Governor's House, including Liangzhou, Xing, Yang and Ji. In the first year of Zhenguan (627), the abandoned government set up a road, and Hanzhong belonged to Shannan Road; In the 21st year of Kaiyuan (733), Shannan Road was divided into east and west roads, Hanzhong belonged to Shannan West Road, and Daozhi was located in Nanzheng (Hanzhong). In the first year of Tianbao (724), Hanzhong County, Yangchuan County and Shunzheng County were established. Later changed to Liangzhou, Yangzhou (now Yangxian) and Xingzhou; In the first year of Xingyuan (784), Liangzhou was changed to Xingyuan Mansion, and Taoism and Mansion were under the jurisdiction of Nanzheng. This was the first time in the history of China that the mansion was named after the emperor. Xingyuan House is the same as Chang 'an in Kyoto, Luoyang in the east and Taiyuan in the north. During the Five Dynasties and Ten Kingdoms period, the former Shu, the later Tang Dynasty and the later Shu successively occupied Hanzhong, and still established Xingyuan County, Waizhou and xing zhou. From the Northern Song Dynasty to the third year of Daoguang (997), Xingyuanfu, Yangzhou and Xing Xing were located in Xiaxi Road. In the fifth year of Xining (1072), Lizhou Road and its affiliated Xingyuan House were located in Hanzhong. Lizhou Road governs the areas south of Qinling Mountains and north of Yangtze River. In the tenth year of Shaoxing in the Southern Song Dynasty (1 14 1), Lizhou Road was divided into two roads: East Road was located in Xingyuan (Hanzhong) and West Road was located in Xingzhou (Lueyang). Houlizhou East Road and West Road have been merged several times. The establishment of Xingyuan Road in Hanzhong in the Yuan Dynasty was the beginning of belonging to Shaanxi. In the third year of Hongwu in Ming Dynasty (1370), it was changed to a mansion and Hanzhong mansion was established. In the Qing Dynasty, Shaanxi-An Road was established in Hanzhong, which governed Hanzhong House and Xing 'an House (now Ankang City).