main idea. A. Mesopotamia was characterized by large, densely-populated urban centers, while the population of Egypt was more evenly distributed across the Nile valley. B. Unlike Mesopotamian city-states, which were culturally and economically distinct, Egyptian villages and towns shared a common language and economy. C. While defense was crucial in Mesopotamian cities due to competition for territory, trade routes, and raw materials, it was less important in Egypt. D. Once they realized that craft production was more profitable than crop production, many Mesopotamians moved from rural to urban areas. E. Differences in settlement patterns help to explain why the Egyptian central government survived and the Mesopotamian city-states did not. F. Trade specialists were evenly spread throughout Egypt, while Mesopotamia's vibrant commercial trade was concentrated in its large urban centers.