Why hasn't Zhu Yuanzhang been in Xi 'an? Because since the Tang Dynasty, the capital must be close to the Grand Canal!

When Zhu Yuanzhang established Daming, Nanjing was the capital, but not the north. Relatively speaking, a unified dynasty will choose the north as its capital, thus controlling the whole country. So why didn't Xi 'an, as an ancient capital, become Zhu Yuanzhang's first choice? There has always been a saying that Prince Wen Yi was killed after only one trip to Xi 'an. The heartbroken Zhu Yuanzhang realized that if he moved his capital to Xi 'an, it would be national subjugation. But it seems that the official history of the Ming Dynasty never said that Zhu Yuanzhang sent his son Zhu Biao to Xi 'an.

In fact, in the Tang Dynasty, Guanzhong declined and the economic and cultural center began to move south. At this time, it is more difficult to choose the capital. Since the Tang Dynasty, the economic lifeline of China was the Beijing-Hangzhou Canal, so all countries in the future should be close to the Grand Canal. So Kaifeng and Beijing are the only capital cities in the north. The alternative capitals in the south are Nanjing and Hangzhou, which are located in the south of the Yangtze River and do not need to rely on the Grand Canal.

If the capital is located in Nanjing or Hangzhou, then the political, cultural and economic centers coincide, just like the former Guanzhong area. But militarily, both Nanjing and Hangzhou are in the southeast, and the threat from China mainly comes from the north, which leads to the separation of the capital from the military center. During the feudal period, the frontier would have too much power, which was a great threat to the central government. So no matter where its capital is, the political, military and economic centers will be separated.

Therefore, one of the reasons why Xi 'an is not suitable to be the capital since the Tang Dynasty is the economic problem! After the Tang Dynasty, the main grain producing areas moved south to the Jianghuai area, and the grain from Jianghuai was transported to Xi 'an. At that time, people pushed horses, and the cost of "logistics" was very high. Excessive cost will lead to social unrest. Seriously speaking: Xi 'an's geographical position is excellent militarily, but after the ancient Tang and Song Dynasties, Xi 'an's economy and culture have lost to the North China Plain and the Jianghuai area in the east, not to mention that the education in the Ming Dynasty was almost monopolized by Jianghuai. Furthermore, on the one hand, Nanjing was the base for Zhu Yuanzhang to become king slowly and build high walls to accumulate grain, on the other hand, it was the center of the south at that time. For the Ming Dynasty, it had enough economic ability to stay away from the remnants of the Yuan Dynasty in the north. Will not waste people and money. Why not? The only disadvantage of Nanjing is that it is located in the southeast, which is not conducive to national control.

Relatively speaking, Xi 'an, the capital of Han Dynasty, was repeatedly harassed by Huns. If it weren't for Liang Wudi's annihilation of the Xiongnu main force, the Han Dynasty wouldn't last long, and military spending alone could bring down the dynasty. Xiongnu is only the strongest, and has no intention of establishing political power in the Central Plains. Otherwise, right Beiping would have been taken away by others, and the Mongols Zhu Yuanzhang faced wanted to annex the Central Plains. Yi Tu is very different. If Xi 'an, whose capital is Xi 'an, and Beiping, and a large area of Shanxi, Hebei, Shandong and Henan are occupied by Mongols and attack from the rear, the enemies who can divide their own land are really terrible enemies. It costs a lot of military money to raise soldiers. If the border defense is unified with the defense of the capital, it will reduce a lot of military spending.

After the Tang Dynasty, Xi 'an had lost power and influence. As long as Luoyang cut off the access to Guanzhong, Xi 'an regime would be unsustainable because it lost the support of southeast wealth. Therefore, in the Five Dynasties and the Song Dynasty, the capital was directly moved to the edge of the Grand Canal, and the granary in Kaifeng was kept, allowing the capital to compete for the Central Plains. There is no river in Xi 'an, so all kinds of materials cannot be transported at low cost, and the radiation to the southeast is insufficient, otherwise it will not move out after Han and Tang Dynasties. Generally speaking, Xi 'an, the capital, can be preserved against civil strife. Therefore, in Xi 'an, the dynasty with its capital was able to go all out to deal with border disputes. Therefore, the Han and Tang dynasties actively defended and attacked the outside world, which made the nomadic people destroy the country many times. During the Song and Ming Dynasties, because of the need to guard against civil strife, we could not adopt the strategy of active external defense, but only passive defense. Therefore, both Song and Ming were internal subjugations.