Xi' an is the most shining business card in China. As the ancient capital of the 13th Dynasty, its fascinating long history, starry ancient ruins and profound cultural accumulation have attracted thousands of tourists from all over the world.

The Tang Dynasty was the heyday in China's history, and Chang 'an, the capital of the Tang Dynasty, was naturally the most glorious period of Chang 'an as the capital. According to historical records, in the prosperous era of Kaiyuan in the Tang Dynasty, the population of Chang 'an had exceeded one million, merchants gathered and the economy was prosperous, with more than 111,111 foreigners settling here alone.

So don't be surprised when you walk on the streets of Chang 'an City in the Tang Dynasty and see people with different skin colors, various clothes and high noses, because Chang 'an has already become a leading international metropolis in the world.

What is puzzling is that since the decline of the Tang Dynasty, it seems that all the emperors and monarchs in the later dynasties have lost interest in establishing Chang 'an as the capital, and Chang 'an has never been the capital since then. So what is the reason for this phenomenon?

Let's take a look at what made Chang 'an the ancient capital of the 13th Dynasty. Chang 'an's geographical location, with many unique advantages, is very suitable as the capital of the Central Plains Dynasty, so politicians and rulers with strategic vision have turned their attention to it.

China has been an agricultural civilized society since ancient times, and the development of agriculture has always been the national plan and the foundation of the country. Fertile land, abundant water and suitable climate are the basic guarantee for the development of agricultural production and the material basis for the survival of the dynasty.

The Guanzhong area where Chang 'an is located has been nourished and watered by tributaries such as the Yellow River and Weihe River since ancient times. It has four distinct seasons: warm in winter and cool in summer. It is rich in products and developed in agriculture. It was the first to win the reputation of "Land of Abundance" written by Sima Qian, and the capital of Chang 'an can first solve the national food problem.

There are many obstacles around Chang 'an, which is easy to defend. To the east of Chang 'an is Huashan Mountain and the Yellow River natural barrier, and stands the famous Hangu Pass. In the south, there are roads isolated by Qinling Mountains, in the west, there are mountains and a series of important passes, and in the north, there are mountains on the Loess Plateau. Therefore, Chang 'an is located in the Guanzhong of the central plain, and it has long been known as the "land of four blockades".

The king who built his capital in Chang 'an only needs to send his troops to guard the danger, so that the enemy can hardly attack even though there are tigers and wolves.

unlike Sichuan, which is remote, Chang' an is not only easy to defend, but also beneficial to attack. Although Sichuan has the natural barrier of Shu Dao, its population is relatively limited and its agricultural infrastructure is backward, so it is more than enough to protect itself, but it can't support the demand of the regime's outward expansion.

In contrast, the Guanzhong Plain where Chang 'an is located not only has fertile fields with a dense population, but also has more mature farming techniques and agricultural facilities and higher agricultural productivity.

more importantly, Chang' an is located in the traffic hub between the east and the west, and its roads extend in all directions. No matter whether it is for cultural exchanges and international exchanges with the outside world or for trade to obtain resources, it has all the geographical advantages. Therefore, when Chang' an makes its capital, it can be said that the advance can be attacked and retreated, and it can be said that it is a land of treasures and dragons and tigers.

the name of Chang' an began with Liu bang, the emperor gaozu. When the Qin Dynasty was tyrannical, the people all over the world were miserable, and they rose up in succession. In the boundless smoke of war, the once majestic Xianyang Imperial Capital also vanished with the Qin Dynasty.

Faced with the ruins, Liu Bang did not choose to enjoy comfort in Luoyang, but embarked on a long journey back to Guanzhong. A few years later, a brand-new capital of the Han Dynasty stood on the land of Guanzhong, and Liu Bang named it "Chang 'an", placing a good wish for the country's long-term stability.

Throughout the history of the Han Dynasty, the border has been very unsettled, especially in the north, where Xiongnu intruded from the south at intervals, and the war spread to only a few hundred miles from Chang 'an. In order to defend Chang 'an, the capital city, the military and civilians of the whole country in the Han Dynasty were United as one, and launched a life-and-death contest with the Xiongnu iron hoof. Through the unremitting efforts of several generations of emperors, by the time of Emperor Wu of the Han Dynasty, the Xiongnu had been beaten by the active Han army and retreated far into the depths of the desert.

In this confrontation between the Han Dynasty and Xiongnu, Chang 'an, on the one hand, helped the Han Dynasty to focus its strategic focus on the front line of the northern war, on the other hand, Chang 'an's impregnable defense system enabled the Han Dynasty to calmly deal with the crisis, and finally created a brilliant achievement of defeating nomadic civilization with agricultural civilization. It can be said that without Liu Bang's vision of making Chang 'an its capital, there would be no power of the Han Dynasty.

after the Han dynasty, many dynasties and political powers established their capitals in Chang' an, and the city scale of Chang' an was constantly expanding. By the heyday of the Tang dynasty, Chang' an had more than one million residents, and the food needed for so many people's daily meals had already exceeded the total grain output of Guanzhong. Even in modern society, it is not easy to supply a big city with a population of one million, not to mention the productivity level and backward transportation conditions at that time.

There is an old saying in China: No grain is transported for a hundred miles, which means that no one wants to make a thankless loss-making business of transporting grain for a long distance, which is heavy, intolerant of storage and cheap. Therefore, the government must come forward to solve the problem of ensuring that there is no shortage of grain in Chang 'an.

In ancient times, the quickest and most cost-effective way to transport grain was by water transport. Every year, the Tang government organized a large number of civilian workers to load the grain collected from the main producing areas such as Shandong and South China on ships, and then dragged it upstream along the Yellow River by manpower, and then transported it to Chang 'an by Weihe waterway.

Although the grain transportation barely solved the grain problem in Chang 'an, its disadvantages gradually emerged.

First of all, it takes a lot of manpower and financial resources to organize trackers every year, which has become a huge financial burden for the Tang government and can only be made up by raising farmers' taxes.

Secondly, the Yellow River waterway is sinister, and the water transportation itself is extremely risky. Especially, a section of the waterway passing through Sanmenxia is fast-flowing, with dense reefs, and there is a "mainstay" to cut off the river. The capsized ships here cannot be counted, resulting in a lot of food losses, which made people feel sad and helpless at that time.

In ancient times, farmers depended on the weather for food, so grain production was easily affected by the natural environment. Coupled with the loss during transportation, despite the government's efforts, food shortage in Chang 'an was still common.

In the history books, there were many records in Sui and Tang Dynasties that "the son of heaven ate", that is, the emperor led a hundred officials from civil and military forces to live in Luoyang in order to alleviate the food pressure in Chang 'an, which showed that the capital was seriously short of food at that time.

In addition to the food pressure brought by the overpopulation in Chang 'an, the huge fuel demand has also caused great damage to the natural environment in Guanzhong area. Because the application of coal has not been popularized, wood as fuel has always been a necessity for people in the Tang Dynasty. In addition, building houses also consume wood. At that time, there were almost no tall trees in Guanzhong, and there were all bare barren hills near Chang 'an.

The destruction of the natural environment has brought about serious problems such as soil erosion and groundwater pollution, which has further reduced the grain output around Chang 'an and plunged into an uncontrollable vicious circle. At this point, although Chang 'an still has the reputation of "the hometown of emperors", it has made generations of emperors reluctant to part with it, but the reality clearly tells them that it is time to find another place.

In the long historical period before the Tang Dynasty, the Yellow River valley has always been the foundation of Chinese civilization, because it is not only the main grain producing area, with mature agricultural production technology, but also developed industrial and commercial handicrafts, prosperous economy and profound cultural accumulation. Besides the narrow areas on both sides of the Yangtze River, the south is basically an undeveloped wilderness.

But this situation changed significantly in the Tang Dynasty. Due to the annexation of land by aristocratic families and landlords, the "land to the tiller" system initiated by the Northern Wei Dynasty collapsed. Many farmers still have to pay heavy taxes because their fields are narrow and barren, or even there is no land to grow, so the overwhelmed farmers have left their homes and fled to the south to survive. Although the Tang Dynasty government's behavior of farmers going south to avoid tax burden was abhorrent, it was precisely because of this phenomenon that objectively greatly promoted the development of the south.

Farmers from the north fled to the south, which not only brought sufficient labor force to the south, but also brought advanced farming and production technology. They opened up wasteland and turned wild land into fertile land with hard sweat, which improved the grain output and population in the south, and at the same time promoted the cultural development in the south through mutual exchanges with local residents. By the middle of the Tang Dynasty, the total economic output of the south had surpassed that of the north, which became the "national destiny" of the Tang Dynasty.

The key reason why the total economic output of the north gradually lags behind that of the south is the Anshi Rebellion. After eight years of war and smoke, all parts of the north have become ruined, people have been displaced and the social economy has been seriously damaged. The south, which was not affected by the war, came from behind, and its grain output and tax revenue became an indispensable pillar for the continuation of the Tang Dynasty.

according to the law of historiography, the movement of economic center will inevitably lead to the shift of political center, so it will only be a matter of time before Chang' an loses its capital status.

Finally, at the end of the Tang Dynasty, the vigorous peasant uprising completely shook the foundation of the Tang Dynasty. Emperor Zhao of the Tang Dynasty waved goodbye to Chang 'an, where his ancestors' tombs were located, and was forced to go to Luoyang by Zhu Wen, the founder of the Back Beam. When he left, under the arrangement of Zhu Wen, all the houses and palaces in Chang 'an were demolished, and the removed wood and building materials were thrown into Weihe River and went eastward along the current, and then they were salvaged ashore near Luoyang to build a brand-new palace in Luoyang. In order to consolidate his rule in Xindu, Zhu Wen ordered the destruction of the walls of Chang 'an and moved all the residents of Chang 'an to Luoyang.

At this point, the political center moved eastward to Henan, and Chang 'an, the ancient capital of the 13th Dynasty, completely lost its status as the capital.

In the long history, Zhu Wen's inhuman behavior seems to be just an accident, but behind the complete abandonment of Chang 'an is an unchangeable historical trend.