Why were rivers important for the growth of cities?

Rivers carry water and nutrients to areas all around the earth. They play a very important part in the water cycle, acting as drainage channels for surface water. Rivers drain nearly 75% of the earth's land surface. Rivers provide excellent habitat and food for many of the earth's organisms.

Rivers provide a constant source of water for industry. They also provide quick access to transportation to engage in the sale of goods to a wider market. They allowed for large trade networks.