There was never a regular supple of water in Mesopotamia but the soil was so enriched, over the years by the layers of silt which a a material deposited by the two rivers! Also an arc of land from the Mediterranean sea to the Persian Gulf Called fertile Crescent!
We have at least three groups, the nobles, the commoners, and the slaves! and about 90% of the people are farmers due to the rich soil this river brings us! In Mesopotamia, each town and city believed to be protected by a god, also the Mesopotamian's believed that these pyramids temples connected to heaven and earth.
social structure and religion
Copper, Tin, and Timber were imported goods exchanged for dried fish, wheat, wool, and metal goods. Industry became an important factor in Civilization as well.