Answer:
Rivers are typically the source of water for many of these regions, which are located in mostly dry, desert lands. After all, water is one of the pillars that sustain life, for without it, animals, plants, and humans would dehydrate and die. As such, many early civilizations found themselves starting near rivers. Egypt, as one of the examples given by the question, started it's civilization near the lush lands of the Nile River, which flooded frequently, providing the land around with nutrient-rich soil called silt, which in turn allowed for the Ancient Egyptians to grow food to sustain their communities. In turn, when a person's needs are met, they would focus more on the betterment of their own lives, which led to the buildup of what can be called civilization today. The same is said for Mesopotamia, which is a region found in between two great rivers, the Euphrates and the Tigris, which provides the region with water and silt for farming, sea life for eating, and even natural barriers during flooding periods against foreign invaders. This allowed for Mesopotamia to, as well, focus on the development of their technology, their culture, and their lifestyle.
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