I agree in part with what you are saying as far as the Sahara desert issue I would refer you to a recent pbs program  skeletons of the Sahara they found a civilization pre dates  Egypt by 5000 years.lakes hippo  alligator elephant fish bones all found with the human remains of a society that is a concrete fact you can it all  buried in the sand not a theory long after the content settled not a computer model or theory along with fact every continent on earth has under water city's off its coast so  these changes have occurred many times in recent history and while humans populated the earth with no cars or factory's so  those of us who do study the concrete facts of the archaeological records  Have more of a clue than you might think also I don't think Egypt or the Middle East were deserts at the time of their great  ancient societies