The document divides history into periods from Prehistory to the Modern Age in order to better understand societal changes over time. It provides details about several early civilizations including Mesopotamia, Egypt, Greece, and Rome. Mesopotamia was located between the Tigris and Euphrates rivers and was divided into city-states that sometimes formed empires. Egypt was located along the Nile River and was ruled by powerful pharaohs. Ancient Greece consisted of independent city-states that were often at war, while Rome grew from a small city to a large empire that conquered many territories through war.