What are the types of modern immigration theories?

Summarize the law of social population migration as follows: 1) Migration is mainly short-distance migration, and long-distance migration is to large industrial and commercial centers. Compared with the center that attracts immigrants, the closer the distance, the more immigrants will move in. On the contrary, the farther the distance, the fewer immigrants move in, and the number of immigrants is inversely proportional to the distance. 2) Migration is often staged. As far as a town is concerned, firstly, people from surrounding rural areas move in, and then immigrants from distant rural areas gradually move into the rural areas around the town; 3) Migration flow and reverse migration flow coexist at the same time, but the net migration flow usually flows from rural areas to cities. In general, immigrants who migrate to a region also have reverse migration; 4) Female groups have certain advantages in short-distance migration; 5) The development of transportation, communication and technology has increased mobility; 6) Favorable economic factors are the most important factors to attract immigrants.