Final answer:
The Sumerians thought of themselves as a civilization and were loyal to individual city-states. They developed extensive trade routes to import materials for construction.
Step-by-step explanation:
The Sumerians thought of themselves as a civilization, they referred to themselves as the "black-haired people" but they were loyal to the individual city-states and the divinities associated with cities. Sumerian cities lacked materials that could be used for construction: hardwoods, stone, and metal had to be imported as were more exotic goods. These things could only be attained by developing extensive trade routes to as far away as western Iran, Syria, and Asia Minor.