1.)
Surplus food -
After the Sumerians developed irrigation systems, they grew more wheat and barley than they needed at one time.
Division of labor -
Large teams of Sumerian workers cultivated the fields, and irrigated and harvested crops. Some continued to farm, but others became carpenters, metal-workers, potters, weavers, merchants, soldiers, doctors, etc.
Cities -
People clustered together in villages and towns to find work, sell their goods, store their grain, and bargain for food. Villages and towns grew into cities as more and more people came together. Ur, Uruk, Kish, Lagash, and Umma are examples of Sumerian cities.
2.) Mesopotamia was in an area that was harsh and unpredictable. There were floods.
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3.) </span>Civilization spreads largely through trade, travel, and warfare. People traveled carrying goods from one region to another and would tell others about new ways of growing crops, making things, and living together. They traded ideas and skills. Although trade brought people into peaceful contact with each other, civilization also spread through wars.<span> </span>
