Ur, one of Sumer's earliest cities, was on the banks of the Euphrates River. About 30,000 people lived in this city. People were divided into social classes and rulers, priests, and priestesses had the most power. It had an agricultural economymany artisans and workers, houses tightly packed on the street, a barter type of trade system, and a temple called a ziggurat. This temple is rituals are perfromed, stores grains, fabrics and gems.