Due to war, financial instability, or some natural disaster.
Explanation:
Population migrations are constant, and throughout history, they are an integral part of human nature. Sometimes the road to a better life can be tough, and hundreds of thousands of people throughout history have lost their lives when going to a better world. People in groups never migrate from natural needs. The reasons for migration are always caused by the inability to live a healthy life.
To best approximate the nature of the movement, it is best to take the example that is currently in the world today. Hundreds of thousands of Syrians are fleeing their own country today to escape the madness of the war that is raging in their country. It is in man's nature that if he is powerless in danger, he reaches for escape, to survive.
So today, a wave of Syrian migrants hit Europe and caused one of the biggest migrant crises in the history of this continent. In addition to Syrian migrants fleeing the war, there are also large numbers of economic migrants. These are those migrants who, due to the weak financial system in their own countries, are fleeing west in search of work and a better life.
Along with Syrians, economic migrants from Algeria, Morocco, Iran, Iraq, Afghanistan, and many other countries are migrating to European countries today. Often throughout history, migrations have also been affected by populations fleeing natural disasters. Natural disasters throughout history have often destroyed entire regions, cities, leading to the movement of survivors in these environments.
