What are the main types and characteristics of population migration?

Population migration can be roughly divided into the following six categories: 1. Work-study type; 2. join the army and demobilize. 3. Types of relatives. 4. Affected by policies. 5. Types of talent flow 6. Types of immigrants in reservoir area

trait

Ancient times: from places with poor natural conditions to places with good natural conditions, a large number of migrations;

Modern: from the founding of the People's Republic of China to the mid-1980s, it moved from the east to the northwest and northeast in a planned and organized way;

Post-80s: from the west to the east, from rural to urban, spontaneous migration, a large number.