The ancient Sumerian civilization formed around 4000 BCE between two large rivers in an area that is now Iraq and Syria. The extremely hot and sunny weather in that area helped crops grow very quickly, but it also made it hard to keep the crops from drying up and dying. So, the Sumerians used water from the rivers in their farming. That method worked so well that they often could harvest even more crops than they needed in a season. As a result, the Sumerians ______blank