Mesopotemian civilization were one of the first people who thrived with agriculture, right there with Egyptians pharaos and the Indus valley people. If we check the geographic location of each one of these people, you will notice that their lands are full of rivers and good soil. In Egypt there's the Nile river, in modern day Iraq, which is where mesopotemia existed, there are 2 main rivers that proved to be essential for the rise of agriculture in the ancient middle east.
I hope this answers your question, and I am at your service if you have any other inquiry about history.