Answer:
The answer is below.
Step-by-step explanation:
The reason we say that it was not natural fertility and high level of food production that was the causes of early urbanization in Mesopotamia occurred in the Southern part of the country, where agriculture was only possible through irrigation.
This made the people of Mesopotamia build their cities along the Tigris and Euphrates and the other branches of these rivers.
Also, it is through this river that aids water transportation that serves as one of the causes for early urbanization in the Southern Mesopotamia region.