They would provide fresh water for crops and for the people who would live near them. Later on, the rivers could be useful for transporting things like crops. And so it's not surprising that our first significant civilizations also emerged where the first agriculture emerged. And our first civilizations we'll see in ancient Egypt along the Nile. We will see it in the Indus Valley along the Indus River. We'll see it in China along the Yellow and Yangtze Rivers. And we'll also see it in Mesopotamia along the Tigris and Euphrates Rivers.