In the Fertile Crescent, we see ample evidence of people migrating from one place to other. Some were coming in, some moving out and some merely in transit.
In the end this produced a fertile interchange of institutional, language and belief from which stems much of human thought and custom even today.
Two reasons for this migration are Over-population and famine.
- Over-population: Sounds funny, since in 4000BC the population of the world has been estimated to be 80-90 million. However, we must look at this number in terms of the available resources and capacity of humans to utilize these resources.
- Famine: Drought could limit an area’s capacity to feed its people and lead to migration. So could other natural disasters like floods, violent storms and even temperatures changes which happen over a longer period of time.
This migration of people lead to interchange of ideas and thoughts which was a very important factor in growth of human civilization.