Why it was difficult to live in Sumer that the foothills?

Living in Sumer was challenging due to its harsh environmental conditions, including unpredictable flooding from the Tigris and Euphrates rivers, which could destroy crops and settlements. The region's arid climate also limited water resources, making agriculture difficult without advanced irrigation systems. Additionally, the lack of natural barriers left Sumer vulnerable to invasions and conflicts with neighboring regions. In contrast, the foothills offered more stable water sources and agricultural conditions, making them more hospitable for settlement.