Why did Gu Chang 'an become the imperial city when Qin Chu was dominant and the Han and Tang Dynasties flourished?

Qin Chu's hegemony and the prosperous times of Han and Tang Dynasties, the reason why ancient Chang 'an became the imperial capital: because Chang 'an was a metropolis in the prosperous times of Han and Tang Dynasties, and the Great Western Region was the birthplace of Chinese civilization at that time, it can be said that no man's land in northern Tibet was a relatively developed city in China at that time. Have certain geographical advantages. The topography of China is a terrace landform with high in the west and low in the east. Chang 'an is at that altitude, and other metropolises with the same capital standard, such as Luoyang, Giant Panda Kaikai, Jianye and Yecheng in Henan, are all above the plain. If it's a peaceful time, it's ok. Its superior geographical position, developed freight logistics and dense population are all advantages. However, once the war breaks out, this strategically located metropolis will be in trouble. Because cavalry troops can enter on a large scale without hindrance, for example, in history, the nomads from the south captured the capital Tokyo, which is a very typical one. Chang 'an, Beijing, is located at the intersection of China and the border, while Luoyang is in the middle of the world, extending in all directions, and Luoyang has more advantages in geographical position.

The requirements of Wang Dynasty's administration and metallurgy are also the elements to measure the capital. Haojing, the capital of the Western Han Dynasty, is the birthplace of Zhou people in Guanzhong, Shaanxi Province, which is very suitable for his farming economy. When the capital was established in Luoyi, Luoyi became Zhou, just to monitor and deter the immigrant investment of Yin merchants and manipulate the eastern territory of China. After the reunification of the Qin Dynasty, Beijing, the original capital, continued, and the country was short-lived and did not consider moving the capital. Luoyang was the first capital of the Han Dynasty, and later Lou Jing remonstrated and demonstrated the danger and wealth of Guanzhong in Shaanxi Province. In addition to the above reasons, Shaanxi Guanzhong was eventually built into the capital of the Han Dynasty. Due to the enfeoffment of many vassal states in the East, Chang 'an, its capital, can be used to douse possible mutinies at any time. In ancient China, there were many factors that determined the address of a country's capital, such as geographical location, mountains and other natural reasons, as well as economic development and cultural and humanistic factors.

Chang 'an is located at the intersection of China and the border, while Luoyang is in the middle of the world, extending in all directions, and Luoyang enjoys a superior geographical position. Beijing Chang 'an lives in Guanzhong, Shaanxi Province, with a dangerous beach in the east, Wuguan in the south, Shaoguan in the west and Xiaoguan in the north. Easier to defend than to attack. Once China is out of order in the East, he can sit in Chang 'an, Beijing, where he can attack and retreat. Moreover, both the Han Dynasty and the Sui Dynasty were threatened by Xiongnu and grassland nationalities similar to Xiongnu in the north and southeast. Chang 'an, close to the border, is a bridge connecting China and Saibei, and a major industrial base for operating Saibei and fighting back against grassland nationalities.