Yanmenguan, known as the 'First Wonder of the World', what makes it so special?

Historically, when the Jin, Hebei, Inner Mongolia and other ethnic groups invaded from the south, they often invaded from the north of Yanmenguan, resulting in more than a hundred wars, including the famous battles between the Xianbei and the Turks, the Five Hu Chaos, the Han-Tang Transition, the Siege of the Northern Song Dynasty, and the Resistance of the Southern Song Dynasty. Since the Ming and Qing Dynasties, there have been dozens of battles between the peasant rebel army led by Li Zicheng and the Qing Dynasty. Therefore, it is known as the 'First Pass of the Great Wall', 'First Barrier of China', 'First Stronghold of the World', 'First Great Wall of China', 'First Wonder of the World', and other reputations. Yanmenguan is one of the longest existing, most complex architectural structures, and most complete and complex military functions in Chinese history. It is located 15 kilometers southeast of Daixian County, Xinzhou City, Shanxi Province, at 32 degrees north latitude. It is the 'Second Throat' of the ancient Great Wall of China, and after Yan and Zhao in Chinese history, it once again became a military stronghold where the Central Plains and the northern minorities traded and competed for high ground. It is a product of the co-progression and long-term coexistence of the Central Plains and the minorities, and also one of the important historical and cultural relics and historical and cultural city cards of the great integration period of ancient Chinese ethnic groups with strategic significance. It has played an immeasurable role and value in studying the formation and development of the ancient Chinese ethnic economy!