It was a water supply for the civilizations within the two rivers. The land was also very fertile and it made it easy to grow food. Lots of vegetation grew there.
You could use rhetoric and rhetorical devices when you would try to persuade someone to do something, like when you haggle at a market and try to persuade why something should change. You could use logos to establish why something is not worth the price and should have a lower price.
The answer is strong governments in towns and villages, and a relatively weak government.
