The Sahara Desert is vast, and very old too. At times in the Earth's history, it had a much wetter climate, and the bones of Sarcosuchus and Ouranosaurus are still sometimes found sticking up out of the dunes. Caves have been found with art showing animals that today only reside in more southern parts of Africa.
When the climate dried up as the Ice Age was ending, people moved to the Nile Valley in large numbers, sparking a great civilization. But the dry air preserves things. The minefields that the Axis and Allies laid down 70 years ago are still there, and still dangerous.
In that same desert the half-insane Persian King, Cambyses II, sent an army to annex the Oasis of Siwa. These soldiers lost their way, and were never heard from again. People have been looking for the army's lost artifacts for centuries.
Cambyses was the son of King Cyrus, who overthrew the last Babylonian Empire and allowed the deported Jewish people to return home.