/kloc-before the 0/9th century, what were the main characteristics of international population migration?

/kloc-before the 0/9th century, the overall characteristics of international population migration were mainly groups and a large number of immigrants. For example,15 ~16th century, the colonial expansion of Europe triggered the migration of more than 70 million Europeans to countries and regions dominated by America and Oceania. These population movements objectively developed the new continent, spread industrial civilization and changed the spatial distribution of ethnic groups. After the Second World War, international population migration has shown new characteristics: population flows from developing countries to developed countries; Settled immigrants decreased, and short-term floating population increased. Europe has changed from a land of emigration to a land of emigration, mainly because the rapid economic development in Western Europe has attracted a large number of immigrants, while Latin America has changed from a land of emigration to a land of emigration, and a large number of people have flowed to the United States, Canada and Western Europe. Since 1970s, oil exporting countries in West Asia and North Africa have also recruited a large number of foreign workers from abroad.