When the ancient emperor ascended the throne and sat in the temple, he paid attention to "facing south and facing north", requiring his back (north) to the mountains and his face (south) to the rivers and plains. To the north of Beijing is the Yanshan Mountains, and to the south is the Yongding River, facing the North China Plain, where the emperor built his capital.
On the one hand, the capitals of Liao, Jin and Yuan Dynasties were built for geomantic reasons, and on the other hand, because these dynasties were all founded by nomadic minorities in the north. In order to effectively rule the Han nationality in the Central Plains, the rulers chose Beijing as the border capital of the Central Plains, but it is very close to the northern grasslands.
Emperor Yongle of the Ming Dynasty moved to Beijing for three reasons: first, because of geomantic omen, Beijing is a blessed land, and mountains and rivers depend on each other; Second, Beijing was the base camp of Emperor Yongle when he was the prince of Yan, and it had a mass base. Third, the emperor protects the country. In the early Ming Dynasty, remnants of the Yuan Dynasty often appeared near Beijing, and the emperor's capital was helpful for effective defense.
The purpose of making Beijing the capital of the Qing Dynasty is to spread ideas to the Han people and prove that the Qing Dynasty is a reasonable and legal successor of the Ming Dynasty and is very close to the Northeast.
In fact, Beijing is indeed a "blessed land": it has never experienced major natural disasters, and earthquakes, droughts, floods and locusts have never hit Beijing on a large scale. Strong cold air from the northwest can also be blocked north of Taihang Mountain and Yanshan Mountain. The typhoon in the south has never crossed Shandong.