It is not only an important military fort to shelter Guanzhong ( the Central part of Shaanxi Province ) areas, but also a key point in the northern strategic defense systems built by Zhongyuan dynasties in the United Period. 它不仅是屏障关中极为重要的军事要塞,而且还是统一时期中原王朝构筑的北部战略防御体系中的关键一环,在中国军事史占有突出地位。