The world's largest (and still growing) desert is not as hostile to human life as one might think. If one knows their way around, it is perfectly possible to navigate the desert, which was once a vast savanna and even today is dotted with oases. The civilizations of Ghana and Mali traversed the desert during the Middle Ages trading gold for salt and eventually converting to Islam.
Recent events in Libya have created new opportunities for archaeologists. Satellite images being used or oil exploration uncovered evidence of an ancient farming civilization that survived by tapping into the groundwater and building a vast irrigation system. See this article from National Geographic for more.
