I am still reading / watching Mesopotamia.. Here among others..
Civilized living in the form of settled farmers and beautiful pottery, seems to have begun in Sumer around 7000 years ago, although the first irrigation canals date to 8000 years ago.
Some 6000 years ago, trade facilitated the rise of many large, temple-centered cities (with populations of over 10,000 people) where centralized administrations employed various workers. It was at this time that Sumerian cities began to make use of slave labor.
These cities were most likely headed by a priest-king, assisted by a council of elders, including both men and women. There was little evidence of institutionalized violence or professional soldiers uptill now, and towns were generally un-walled. During this period Uruk became the most urbanised city in the world, surpassing for the first time 50,000 inhabitants.
The dynastic period began some 5000 years ago and was associated with increased violence. Cities became walled, and increased in size as undefended villages in southern Mesopotamia disappeared. The now deciphered syllabic writing started to develop from the early pictograms.
In conclusion then, warfare was not a part of the civilization that existed in Sumer from 7000 – 5000 years ago.