There are various reasons that have caused population movements throughout our history, what is the most direct reason?

After a long period of population growth in the interior of the country, the population reached saturation and it was impossible for everyone to have land to grow. So the peasants in Shandong and Hebei to make a living, they went to the sparsely populated Manchu "Longxing land" to pan for gold, planting. The beginning of the Guandong period was in the early and middle of the Qing Dynasty, not in the late period. Guandong, that is, east of Shanhaiguan, part of today's Liaoning Province, and Jilin, Heilongjiang, when there is also part of the land was later seized by the Czarist Russia. Since the Qing dynasty forbade the Han Chinese from entering the Guandong, the Han Chinese had to "break in".

The land in the north of Shanxi is barren, frequent natural disasters, the survival of the harsh environment forced many people in the north of the Jin Dynasty to make a living outside the mouth. "Hequ BaoDeZhou, ten years nine not harvest, the man go outside the mouth, the woman digging wild vegetables" of the old Shanxi ballad fully explains the "go west mouth" for natural disasters caused by the starving people. Qing Guangxu three to five years, Shanxi and other provinces in three years of drought, known as the "Dingwuqi disaster" of the most serious drought in modern times, and even part of the area did not rain. Natural disasters caused by population displacement, Xinzhou, Yanbei and other northern Jinbei region is the most prominent. Jinbei counties barren land, poor natural environment forced a large number of people to leave their homeland. For example, "Yang Gao is located in the North Block, moraine excellent very, high soil and yellow sand, full of low soil, alkali halogen difficult to plow ...... barren people poor, nothing thick hide, a case of barrenness and failure, the displacement is unbearable." In the barren land, cold climate, no Chuanliu irrigation in the harsh natural environment, Jinbei people live in hardship. Whenever there was a disaster or failure, people had to be displaced and went outside their mouths to make a living. "Going West" is a bitter history of immigration, is a history of hard work and entrepreneurship. Batch after batch of immigrants left their hometowns and went north to Mongolia, and worked hard to develop the Inner Mongolia region. More importantly, they are in a backward nomadic state of Inner Mongolia in the middle and western part of the advanced farming culture, so that the whole local cultural landscape has undergone a fundamental change. Along with the migration process of "Going West", the Mongolian region outside the mouth has evolved from a traditional single nomadic society to a pluralistic society in which both counties are established and farming is practiced. In this process of evolution, Shanxi immigrants, as the main body of immigrants, made a great contribution. As immigrants from Shanxi accounted for the vast majority of immigrants, the local immigrant culture was characterized by Jin culture, which can also be said to be the expansion of Jin culture in this region. Population mobility has led to the spread of culture, and the spread of culture has narrowed the distance between regions and strengthened their sense of identity. "Go West" this wave of immigration, greatly promote the communication between the central and western regions of Inner Mongolia and the mainland, and further enhance the national feelings between the Mongolian and Han Chinese, on the prosperity and stability of our multi-ethnic country has had a certain positive impact.