What is the effects of deserts and rivers for Mesopotamia and Egypt

The deserts helped the Egyptians because the deserts have scorching heat. The large desert areas were not favorable to humans or animals. This kept Egypt isolated from outside invaders. The Nile River's physical features also provided protection. The delta marshes stopped invaders who sailed from the Mediterranean Sea. Also the Nile's cataracts prevented enemy ships from attacking Egypt. Because of these physical features the Egyptians rarely faced the danger of invasion.