@Mudkipz and Darvince: You two haven't even selected an area yet.....
Also, why should we be restricted to the fertile cresent? Theres several other areas that are the cradle of civilization(s), Mesoamerica (central america, yucatan pennensula), Indus river valley (India), and the Yangtze river and Yellow river valleys (eastern China).
There could be other regions since theres other places where cultures flourished, but those are the big ones.