1. The origin of Xijing is the product of ancient Beijing system.
Due to China's vast territory, diverse ethnic groups and long history, with the expansion of the national territory, in order to facilitate governance, the form of "1+X" will be implemented in a certain period of time, that is, one capital plus multiple capitals. In the multi-Beijing system, in order to balance things, there are capitals named after their locations, namely Xijing, Tokyo, Nanjing and Beijing. Therefore, in a broad historical sense, Xijing, like other titles, does not simply refer to a fixed geographical location, but is formulated according to the size of the country's territory and the focus of governance.
The three capitals system appeared for the first time in the Eastern Han Dynasty, except Luoyang as the capital, Xijing as Chang 'an and Nanjing as Nanyang. During the Cao and Wei Dynasties, the five capitals system was implemented, and Luoyang was still the capital, with Chang 'an, Qiaocheng, Xuchang and Ye Jing as the four capitals. Among them, Chang 'an is Xijing, Qiaocheng (now Bozhou, Anhui) and other places are Cao Cao's hometown, Xuchang is the foundation of Cao Cao's prosperity, and Yecheng (now Linzhang, Hebei) is the foundation of Cao Cao's career. Cao Wei's five capitals system is basically set around Cao Cao's life.
The Tang Dynasty was the most prosperous period of multi-Beijing system, which was basically based on the three-Beijing system and five-Beijing system around Chang 'an and Luoyang. This parallel form of multi-capitals was caused by the instability and war in the Tang Dynasty, and the establishment of the five-capital system facilitated the emperor's refuge. For example, Wu Zetian was originally Beijing, Chang 'an was Xijing, and Luoyang was Tokyo. On the basis of the same things in Beijing, Emperor Xuanzong of the Tang Dynasty designated Zhou Pu as Zhongdu and Taiyuan as Beijing respectively. By the time of Su Zong, the five-capital system had begun to take shape. Apart from Chang 'an as the capital, there were Luoyang in Tokyo, Fengxiang in Xijing, Shujun in Nanjing and Taiyuan in Beijing.
It is worth noting that the system of five capitals in the Tang Dynasty led the frontier minorities to follow suit at that time, so the name "Xijing" also included other meaning in the history books. For example, Bohai Kingdom (now northeast China, North Korea and Russian Far East) set up five capitals in imitation of the suzerain Tang Dynasty, and went to Beijing Longquan House, Beijing Xiande House, Tokyo Long Yuan House, Nanjing Nanhai House, Xijing Yalu House and Xijing House here. There is also Nanzhao State (Erhai Lake in Yunnan), which is also a five-Beijing system, but the territory is too small, and the east, west, north and south are not so clear.
Great changes have taken place in Xijing in the Five Dynasties. In the later Tang Dynasty, the system of four capitals was implemented, with Yecheng as its capital, Tangfu in Tokyo, Taiyuan in Xijing, Zhou Zhen in Beijing (Zhengding in Hebei), and then Sanjing as its capital, Luoyang as its capital, Jingzhao House in Xijing and Taiyuan House in Beijing. In the late Jin Dynasty, the four capitals system was implemented, with Kaifeng as Tokyo and Xijing Luoyang, Beijing Taiyuan and Yecheng as the capitals. After the Han Dynasty inherited the latter Jin Dynasty, Kaifeng was still regarded as Tokyo, and Xijing Luoyang, Beijing Taiyuan and Yeduxing Tangfu were regarded as capitals.
Because the Song Dynasty never completed the unification of China, its territory was relatively small, but the factors of foreign enemies in the region needed to be considered, so the multi-Beijing system was also implemented. The Northern Song Dynasty adopted the four-capital system. Apart from the capital Bianjing, there are three supporting capitals: Xijing Henan House, Nanjing Yingtianfu House and Beijing Daming House. The Southern Song Dynasty was even worse, just a capital city. At the same time, Liao and Jin dynasties also implemented the five capitals system, and the Jin dynasty was more prominent. Besides attending Huining Mansion in Beijing, there are six other capitals in Beijing, including Huanglin Mansion in Beijing, Dading Mansion in Beijing, Liaoyang Mansion in Tokyo, Datong Mansion in Xijing and Xijin Mansion in Nanjing. The Yuan, Ming and Qing Dynasties realized the unprecedented unification of China's territory. However, due to its strong political, military and economic power, the multi-Beijing system was more about form than content.
Tang Dou is simply the capital of Tang Dynasty.
In a broad sense, Tang Dou is the capital of the Tang Dynasty. In other words, all the cities designated as capitals and capitals are Tang Dou, so the cities under the "three capitals" system of the Tang Dynasty can be called Tang Dou, not Xi 'an.
The capital of the Tang Dynasty surrounded Chang 'an and Luoyang as a whole. Therefore, there is no doubt that Chang 'an and Luoyang belong to Tang Dou. In addition, Wu Zetian took Bing, today's Taiyuan, as Beijing, and Tang Xuanzong took Hezhou, now Zhou Pu, as Beijing. Therefore, both Taiyuan and Zhou Pu, in the eyes of the rulers of the Tang Dynasty, were the birthplace of the Tang Dynasty and the land of Longxing, so they were designated as the capital.
In addition, it is worth noting that the capital of the Five Dynasties and the end of the Tang Dynasty is also called Tang Dou in a sense, so Yecheng, Tangfu in Tokyo, Taiyuan in Xijing and Zhou Zhen in Beijing are also attached to Tang Dou in today's tourism development. Of course, in this sense, Jinling (now Nanjing), the capital of the Southern Tang Dynasty, can also be regarded as Tang Dou, but Jinling is famous enough, with more dynasties and years as the capital than that of the Southern Tang Dynasty. Therefore, Jinling will not rub the heat of "Tang Dou".
3. People's familiarity with Xijing and Tang Dou is closely related to the length of their capitals.
In a word, Xijing and Tang Dou refer to Xi 'an in a narrow sense, but Xijing in some dynasties, and even some capitals in the Tang Dynasty, are not well known because the capital was established in a short time. Therefore, if we want to analyze the origin of Xijing, we must clarify the ancient multi-Beijing system, in which Xijing was not limited to Chang 'an, but a city with strategic significance in its geographical position at that time. On the other hand, Tang Dou can be simply understood as the capital of the Tang Dynasty. Therefore, except Chang 'an and Luoyang, other cities can be excavated, which is of great benefit to local tourism.