Why did the ancient capital of China move from west to east?

There are different reasons for the eastward movement of ancient capitals, and it is not a law. Take the capital of China ancient unified dynasty as an example.

according to the changes of the five ancient capitals, we can see that three ancient capitals, Xi' an, Luoyang and Kaifeng, are arranged horizontally in the central part of China, just on the south bank of Weihe River and Yellow River, which are the heartland of the ancient Central Plains, while two ancient capitals, Beijing and Nanjing, are arranged vertically in the eastern part of China and located on the edge of the ancient Central Plains. If we distinguish by time, the three ancient capitals in the center of the Central Plains were established before the Northern Song Dynasty, which is equivalent to the early stage of China's feudal society. Beijing and Nanjing, which are located on the edge of the Central Plains, were established in the Yuan, Ming and Qing Dynasties, which is just the late stage of China's feudal society.

the capital of the unified dynasty moved eastward from Chang' an and Luoyang to Kaifeng for economic reasons, which was the continuation and development of the Emperor's leaving Chang' an for Luoyang since the Sui and Tang Dynasties, with the focus on obtaining grain and consumption materials more conveniently. From a political point of view, it is also of great significance to move the capital to the east. Since the late Tang Dynasty and the Five Dynasties, the south has become the focus of China's economy, and its political importance is also rising. During the Five Dynasties and Ten Kingdoms period, the world was torn apart. However, after a little analysis, we can see that the north is five dynasties, and although the dynasties changed frequently, they were still generally unified under the banner of one emperor; Of the ten countries, nine are located in the south, and only one country (Northern Han Dynasty) is located in present-day Shanxi Province in the north. Therefore, the so-called separatist situation mainly refers to the separatist regime in the southern region. Putting the capital in Kaifeng, which is close to Jianghuai, is also convenient to control the southern region, which is the center of national economy and easy to split.

after the yuan dynasty, Beijing replaced Kaifeng as the capital of the unified dynasty, which can be said to be mainly produced in the context of national struggle.

both the yuan dynasty and the Qing dynasty were established after the frontier ethnic groups in China entered the central plains. the yuan dynasty was founded by the nomadic Mongols from the Mongolian grasslands, and the Qing dynasty was founded by the semi-hunting and semi-farming Jurchen ethnic group from Heishui, Baishan, Northeast China. The area where they used to live was sparsely populated, economically backward and with a low degree of social development. It was mainly attracted by the advanced economy and culture in the Central Plains that they entered the Central Plains step by step. Therefore, when they occupy the North China Plain, which is densely populated and rich in products, it is natural to focus on management and build it into a base for further southward movement. On the other hand, Shenyang, the capital of the early Qing Dynasty, and Kaipingfu, the original capital of the Yuan Dynasty, are almost thousands of miles away from the Central Plains, and the traffic is inconvenient, which is not conducive to ruling the Han nationality areas nearby. Beijing is the first and most important city they captured in the Han area, and it is also an important town in the northern part of North China Plain. Taking Beijing as the capital is convenient for controlling North China and capturing all of China. Historically, the Yuan and Qing Dynasties took Beijing first, then North China, and unified China after making Beijing their capital.