Map of Egypt showing ancient desert routes:
Prehistoric Swimmers in the Sahara
Pauline de Flers, Phillippe de Flers, and Jean-Loïc Le Quellec (2007)
Arts et Cultures, Revue des Musées Barbier-Müller, 2007 : 46-61
"The Neolithic Age underwent a long period when atmospheric conditions made life impossible in the dessert. A less arid stage followed over several millenia when desert populations began to settle and civilizations developed. Then a period of renewed dryness set in and these populations were forced to emigrate to the south and also east toward the Nile Valley."
"Recent twenty-first century discoveries have given rise to a series of new questions. Were these movements really as one-directional as previously believed? Could a return to the desert have been possible in spite of the extreme drought conditions that caused the initial exodus? And, what overwhelming attraction could have driven these people to re-confront such conditions?"