There were several reasons due to which civilizations arose in the valleys of Tigris and Euphrates rivers. The river banks were fertile and supported a healthy growth of crops. These crops were enough or rather more than enough to support the people of the civilisation. The water of these rivers also had a good amount of marine life, which included fish for eating. These are the basic requirements for supporting a civilization. The rivers also served as a good means of transport. People of those civilization were able to create boats and used the river for transportation.