| A | B |
|---|
| Mesopotamia | in ancient times, the geographic area located between the Tigris and Euphrates Rivers |
| Sumer | an area in the southern part of Mesopotamia, where cities first appeared |
| city-state | an early city that was like a small, independent country with its own laws and government |
| irrigation system | a means of supplying land with water |
| levee | a wall of earth built to prevent a river from flooding its banks |
| fertile soil | soil rich in minerals needed to grow crops |
| silt | fine particles of rock |
| civilization | a culture marked by developments in arts, sciences, government, and social structure |
| history | record of what has happened in the past |
| prehistory | period of time before writing |
| primary source | first-hand accounts of an event |
| artifacts | objects that were made by people long ago |
