The most important reason is economic opportunity. You may have moved or your family may have moved in their lifetime, and chances are it was for an economic opportunity. Perhaps your mother or father got a new job or couldn't find a job where you were living, or your guardian was transferred or something like that. That tends to be the reason why most people move today is for better economic opportunities. Some people are looking for resources. This is very common in ancient times. If a river were to dry up or a water source would be gone, civilization would be forced to move on to find more resources. More land is another reason people migrate. That was a very popular reason for the settlement of the Western United States. Lots of settlers came from not only within the United States, but around the world in order to own their own land. Forced migration is another reason for migration. People, ethnic groups especially, have been victims of being expelled from a region and having to relocate by force. Other groups have chosen to relocate because of other forced reasons, such as disease epidemics or because of war. So all of these reasons are part of the reasons why people either have to move or choose to move, not only in the past, but also today.
