For the early Egyptians there was supposedly no water west of the oasis towns. The world ended out there. The interior was waterless. But in the emptiness of deserts you are always surrounded by lost history. Tebu and Senussi tribes had roamed there 

possessing wells that they guarded with great secrecy. There were rumours of fertile lands that nestled within the desert’s interior. Arab writers in the thirteenth century spoke of Zerzura. “The Oasis of Little Birds.” “The City of Acacias.” 

Look at a map of the Libyan Desert and you will see names. Kemal el Din in 1925, who, almost solitary, carried out the first great modern expedition. Bagnold 1930-1932. Almasy-Madox 1931-1937. Just north of the Tropic of Cancer.