early civilization ?

Historians generally say the earliest civilizations existed in northern Africa and in the Middle East around the Mediterranean. Isn't this inconsistent with historical sociology ? Don't people generally congregate around water in lush, green, fertile areas ? Why would people stay in an area that, as far as we know, has always been dry, brown, rocky and desert like ? Especially when the Fertile Cresent is not far away ?

I know other early civilizations existed in other areas of the world that were seemingly more fertile. But, according to my research, the earliest were in northern Africa and in the Middle East around the Mediterranean.