Explain why people living in the northern areas of the Fertile Crescent moved into other areas? What finally allowed people to settle in southern Mesopotamia?

People living in the northern areas of the Fertile Crescent moved into other areas due to a variety of factors, including climate change, overpopulation, and the search for new resources. Climate change caused a decrease in rainfall, leading to a decrease in the availability of food and water. Overpopulation also caused people to move in search of new resources and land. Finally, the development of irrigation systems in southern Mesopotamia allowed people to settle in the area and cultivate crops, providing a more reliable source of food and water.