Rub' al Khali desert, Saudi Arabia [huanqiu.com]

11. The Rub' al Khali (Empty Quarter) desert, covering about 250,000 square miles (650,000 square km) in a structural basin lying mainly in southeastern Saudi Arabia, with lesser portions in Yemen, Oman, and the United Arab Emirates. It is the largest area of continuous sand in the world. It occupies more than one-quarter of Saudi Arabia.

For several centuries, the Bedouin communities have been the only people with the skills to survive in Rub al-Khali's wild desert. They raise livestock with the local vegatation. But the ecological systemhere is very fragile due to the surging temperature.