In this lesson plan students discuss how the changing natural environment can become a source of conflict between some groups within a society. Discuss with students how using the rivers for irrigation caused conflict between the Sumerian city-states. What ways, other than warfare, might the Sumerians have used to solve this problem? The Assyrians and Babylonians relocated conquered peoples, moving them far away from their homelands. Discuss how this policy compares with the United States government's historic removal of Native Americans from their homelands to reservations. Were the reasons for these removals similar? How are they different?