A quarter of the peninsula
Ar-Rub' al-Khali covers about 550,000 km² of the south-eastern Arabian Peninsula, shared by Saudi Arabia, the UAE, Oman and Yemen. About 430,000 km² lies in the Kingdom, 22% of its area and 67.7% of its sand formations, divided between the Eastern Province (about 65%), Najran (about 25%) and Riyadh (under 10%). Within Saudi borders it stretches up to 1,200 km long and 650 km wide.
Its name reflects how few people, animals and plants it can support. Al-Ahqaf, its southern part, is believed to be the homeland of the people of Ad.
Dunes and sabkhas
Reddish-golden dunes rise up to 210 m above the ground, and in the north-east, near the UAE border, the crests of the Shaybah dunes stand up to 200 m above their surroundings. Between them lie salt flats; the largest, Sabkhat al-Humr, sits about 24 m below sea level and measures roughly 20 km by 7 km.
This is the hottest and driest part of the Kingdom. Rainfall averages under 50 mm a year, two or three years can pass without any, and summer temperatures exceed 50°C. Calligonum, whose taproots reach deep water and help hold the dunes in place, is its commonest plant.
Protected corners
Two reserves guard its wildlife: Shaybah, 637 km², managed by Saudi Aramco, and Uruq Bani Ma'arid, 12,787 km², in the south-west, run by the National Center for Wildlife.