What geographical feature most contribute to the growth of ancient Egypt and Mesopotamia?

The growth of ancient Egypt was significantly influenced by the Nile River, which provided fertile soil through annual flooding, facilitating agriculture and enabling civilization to thrive. In Mesopotamia, the Tigris and Euphrates rivers played a similar role, offering irrigation and rich alluvial plains that supported agriculture. Both regions benefited from these rivers, which not only supplied water but also served as trade routes, fostering economic and cultural development.