Driving through the vast, sun-bleached landscape of Mauritania, you'd be forgiven for expecting to see a tricked-out post-apocalyptic hot rod from Mad Max on the horizon. Instead, a solitary, turbaned figure tending a herd of goats tells the story of survival amid millennial-old geological forces. Mauritania, with one of the world's lowest population densities, is almost equally divided between Moors of Arab-Berber descent and Black Africans, a striking cultural combination that is part of its appeal.