Geography
The world's largest sand desert is roughly the size of France
The Rub' al Khali, or Empty Quarter, covers about 560,000 square kilometres of the southern Arabian Peninsula — the largest contiguous expanse of sand on Earth, with dunes rising over 250 metres. It went essentially unexplored by outsiders until the 20th century, yet fossils of hippos and long-horned cattle buried in its sands show it was once a green, lake-dotted savanna.