The Ilo Valley where Luoyang is located is relatively narrow, the economic center of Shandong is not here, and the agricultural production in Luoyang area is not very developed. But Luoyang's good geographical location and traffic conditions have become its greatest advantage. As mentioned earlier, during the Sui and Tang Dynasties, the economic center of China had already begun to be out of touch. At that time, the main grain producing areas were Shandong and Jianghuai areas in the lower reaches of the Yellow River, and the grain in Kyoto relied heavily on transshipment between the two places. When Emperor Yangdi Yang Di dug the Grand Canal, Yongji Canal and Tongji Canal respectively extended to the northeast and southeast with Luoyang as the center. Luoyang has become the hub of the Grand Canal and the largest grain distribution center in China. There were two granaries in Luoyang in Sui Dynasty, namely Jiacang and Luokou, but the grain was not used up during Zhenguan period in Tang Dynasty. If the grain is transported from Luoyang to Chang 'an, it will not only take more than 1000 miles, but also capsize accidents often occur in Sanmenxia area. The simplest way to solve this difficulty is to move the capital to Luoyang.
During the reign of Yang Di, he spent most of his time in Luoyang, the eastern capital, which replaced Daxing City as the actual capital. In the Tang Dynasty, the political center changed frequently between Chang 'an and Luoyang for a long time. However, due to the northwest frontier, Chang 'an has been the capital for a longer time than Luoyang. Luoyang controls the east, but it is too far from the northwest to deal with emergencies in time. Moreover, in the late Tang Dynasty, Luoyang was located in the land of four wars, and its usual advantage became a disadvantage in wartime. Therefore, during the Sui and Tang Dynasties, Chang 'an and Luoyang were established politically and militarily, and were easy to defend but difficult to attack, so they could open up the western regions to the west as a buffer zone to prevent grassland nationalities. The other is based on the transportation economy, extending in all directions, and the world has the benefits of water transportation. From the late Tang Dynasty to the Five Dynasties, the political center moved from Chang 'an to Luoyang, and from Luoyang to Kaifeng. On the one hand, it reflected the shrinking trend of the Central Plains dynasty in frontier defense, on the other hand, it also reflected that the political power greatly increased its dependence on fiscal revenue in the southeast. After the diversion of the Grand Canal, Kaifeng became a new shipping center. In the early years of the Northern Song Dynasty, Song Taizu had planned to move the capital to Luoyang first, and then to Chang 'an. However, due to the policy of strengthening cadres and weakening branches in the Northern Song Dynasty, half of the imperial army in Kaifeng was concentrated, and all of them relied on the Grand Canal to transport grain and grass. At this time, Chang 'an and Luoyang have declined, and most of their original advantages are gone, so they can't accommodate the huge population, so they have to give up their capitals. In the late period of ancient society, the northwest frontier was gradually replaced by the northeast frontier, and the capital of the Central Plains regime began to move eastward, guarding the north-south traffic arteries and facilitating border defense. For example, Beijing was the capital of the Ming Dynasty. This made Chang 'an and Luoyang lose their qualifications as capitals forever.
In addition to these factors, the political needs of the dynasty also determined the location of its capital. Haojing, the capital of the Western Zhou Dynasty, is the birthplace of the Zhou family in Guanzhong, which is very suitable for their farming economy. When the capital of Luoyi was established, Luoyi became Zhou, with the purpose of monitoring and deterring the immigrants of Shang Dynasty and controlling the eastern territory. After the reunification of the Qin dynasty, the original capital was used, and the country was short-lived, so the problem of capital migration was not considered in time. The capital of the Western Han Dynasty was originally in Luoyang, and later Lou Jing remonstrated, urging the danger and wealth in Guanzhong. In addition to the above reasons, the Western Han Dynasty finally made Guanzhong its capital, and because a large number of vassal states were enfeoffed in the east and made Chang 'an its capital, it could put out possible rebellions at any time. Emperor Guangwu of the Eastern Han Dynasty set out from Hebei, and then attacked Luoyang in all directions to pacify the world. Most of the heroes in Liu Xiu's novels are Nanyang strongmen. The Eastern Han regime relied on the support of the strongmen, and Luoyang was also located in their base areas. However, the Eastern Han Dynasty still regarded Chang 'an as the eastern capital, and most emperors went to Chang 'an every year to pay homage to their ancestors' tombs. However, during the Eastern Han Dynasty, the decline of Chang 'an's status inevitably had some negative effects. The control over the frontier was weakened, and the rebellion of the Qiang people was completely suppressed until the demise of the Eastern Han Dynasty, and Sanfu area became the residence of Rongdi who moved inward. By the time of the five riots, the proportion of Hu people and Han people in Guanzhong was unbalanced. Cao Cao's political center controlled Yecheng, an important town in Hebei and Hedong. When Cao Pi ascended the throne, he chose Luoyang, which had been abandoned for many years, as the capital, mainly because Luoyang was close to the south, which was convenient for fighting Wu. The pre-Qin Dynasty was founded by the Di nationality who lived in the border area of Sichuan, Shaanxi and Gansu for a long time, and there was also a considerable population in Guanzhong. Chang 'an, the capital of the former Qin Dynasty, was also related to its proximity to the place where its ancestors lived. Emperor Xiaowen of the Northern Wei Dynasty moved south, and his destination was changed from Yecheng to Luoyang, which was also located in the south, which was convenient to fight against the Southern Dynasties. Moreover, Luoyang, as the ancient capital of the traditional Han dynasty, has great influence and sense of belonging among the Han people. The Northern Wei Dynasty took Luoyang as its capital, which could not only win over the Han nationality effectively, but also pretend to be China orthodoxy, which showed Emperor Xiaowen's determination to fully sinicize. The founding fathers of the Northern Zhou Dynasty, Sui Dynasty and Tang Dynasty were all born in Guanlong military nobles, and Guanzhong was their traditional base. At the beginning of the Tang Dynasty, there was a struggle among the Long clan, the Shandong clan and the Han clan. Wu Zetian made great efforts to appoint officials from Shandong, suppressed the gentry in Guanlong, and moved the capital from Chang 'an to Luoyang, reducing Chang 'an's political status and avoiding being contained.
So generally speaking, the advantage of Chang 'an lies in the terrain, and the advantage of Luoyang lies in the traffic. Typical dynasties with Chang 'an as their capital, such as the Western Han Dynasty and the Tang Dynasty, became the most brilliant and internationally influential dynasties in ancient China. Chang 'an is located in the northwest, and is in the front line of fighting against the grassland people. Its capital Chang 'an has also become a symbol of an export-oriented dynasty. Luoyang, on the other hand, is located in the middle of the Central Plains, far from the frontier. The administration of the dynasty was mainly in the mainland, and it often had little effect on expanding the territory.