The Arabian and Middle Eastern Deserts

The Rub' al Khali, or "Empty Quarter," is the largest contiguous body of sand on Earth, an erg of roughly 650,000 square kilometers spanning Saudi Arabia, Oman, the United Arab Emirates, and Yemen, with dunes reaching heights of 250 meters. Its hyperaridity results from its position beneath the subtropical high-pressure belt, reinforced by the warm, evaporative waters of the Arabian Gulf and the Red Sea, which paradoxically add little rainfall while amplifying regional heat. The British explorer Bertram Thomas completed the first recorded Western crossing of the Empty Quarter in 1930-31, followed shortly after by St John Philby in 1932, and later by Wilfred Thesiger's celebrated 1946-1950 journeys recorded in his book Arabian Sands (1959).