Why did "going west and going east" become synonymous with the immigration tide in China's modern history?

Westbound is one of the five most famous migration events in China's modern history. In the long history of more than 400 years from the mid-Ming Dynasty to the early Republic of China, countless Shanxi people, Shaanxi people and Hebei people left their homes, which opened up the economic and cultural channel between the hinterland of the Central Plains and the Mongolian grassland and promoted the prosperity and development of the northern region.

In the last years of China's feudal dynasty, ordinary people who could not bear the war and former nobles who lost power emigrated overseas. Due to its geographical proximity, Southeast Asia has become a place of immigration and refuge for China immigrants. Therefore, this migration is called "Lower South Asia" in history.

During the late Qing Dynasty and the Republic of China, due to natural disasters and the Qing government's call for immigrants, a large number of people in the Central Plains and Jiangbei areas were forced or took the initiative to cross Shanhaiguan and Bohai Sea to travel to the Northeast, reclaim land and settle down.