They would dig ditches from a river to their crops to make sure they got water to grow. Another important key to a successful civilization is government, ability to keep a social order and balance; division of labor and communication. The government is there for the people, to protect them. Division of labor, because when there are multiply doing different jobs a project getting completed more efficiently, opposed to multitude of people on one job. A good example of this would be Sumer in Mesopotamia. Not only did the Sumerians, have a complete understanding of trading they had some-what of a social structure by 2500 B.C. By 5000 B.C. the Sumerians were in the process of developing a writing system witch had evolved into pictograms and kept records by means of scribes.
Sumer reached its height in civilization in its third millennium. But like most things good, it began to decline. Water that was used to water the crops was poisoned through a process known as salinization. Crops didnt grow as well and as often. Without water and a steady source of food, within 500 years to the food production dropped to an all time low. Nonetheless the legacy left by the Sumerians created, the default idea of civilization they left, would be used in the years to come.