3800 B.C. Counted Time Zodiac Calendar of Nippur Was Granted to Mankind.

A New Social Structure 

    A new social structure based on economic power also arose. Rulers and an upper class of priests, government officials , and warriors dominated society. Below this upper class was a large group of free people--farmers, artisans and craftspeople. 

At the bottom was a slave class.  

Abundant food supplies created new opportunities, enabling some people to work in occupations other than forming. The demand of the upper class for luxury items encouraged artisans and craftspeople to create new products . As urban populations exported finished goods to neighboring populations in exchange for raw materials, organized trade began to grow.   Because trade brought new civilizations into contact with one another, it often led to the transfer of new technology from one region to another. 

    By and large, however, the early river Valley civilizations developed independently. Each one was based on development connected to the agricultural revolution of the Neolithic Age and the cities that this revolution helped  to produce. Taken together, the civilization of Mesopotamia, Egypt, India, and China constituted Nothing less than a revolutionary stage in the growth of human society. 

Source: Glencoe World History, publish 2004, edition 2, page 31.