The desert stretches roughly 1,000 kilometres in length and 500 kilometres in width, occupying the area between longitudes 44.5° and 56.5°E and latitudes 16.5° and 23.0°N. Surface elevation varies from approximately 800 metres in the southwest to near sea level in the northeast. The dominant terrain consists of ergs — vast sheets and seas of sand dunes — rising to heights of 250 metres, interspersed with gravel plains, gypsum flats, and brackish salt formations known as sabkhas.
The sand carries a distinctive reddish-orange colouration resulting from the presence of feldspar. Along the middle length of the desert, hardened calcium carbonate formations mark the sites of ancient shallow lakes that existed between 6,000 and 2,000 years ago, fed by monsoon-like rainfall during those prehistoric wetter periods. The current climate is hyper-arid, with annual precipitation generally below 50 millimetres and relative humidity as low as 15% during summer months.
Since the Dakar Rally relocated to Saudi Arabia for its 2020 edition, the Rub' al Khali dune fields have formed the centrepiece of the event's most technically demanding stages. The scale and continuity of the dune sea present navigation and vehicle management challenges that organisers consider comparable to the Saharan stages of the original African era. Dunes of 200 metres or more require competitors to read approach angles, manage momentum across crests, and avoid becoming beached in soft sand bowls between ridges.
The January timing of the Saudi Dakar corresponds to the Rub' al Khali's cooler season, with daytime temperatures reduced from the summer extremes of over 50 degrees Celsius. Even so, conditions remain harsh and mechanical failures from sand ingestion remain a primary cause of retirements. The dune formations in the Rub' al Khali are reported to maintain their essential shape over time, as prevailing winds blow sand off surfaces without causing the dunes themselves to migrate significantly — a characteristic linked to moisture drawn upward from surrounding sabkhas.
The Rub' al Khali has been inhabited at its periphery by tribal communities including the Al Murrah, Banu Yam, and Bani Yas for centuries, though its interior was considered impenetrable by outsiders until the early twentieth century. The first documented crossings by non-resident explorers were made by British travellers Bertram Thomas and St John Philby in the early 1930s. Wilfred Thesiger crossed the area multiple times between 1946 and 1950, mapping large portions of the interior as described in his 1959 book Arabian Sands.
Scientific expeditions have yielded significant discoveries. A 2006 Saudi Geological Survey expedition of 89 scientists identified 31 new plant species and 24 bird species, along with meteorite finds. Fossil evidence indicates that the region supported hippopotamus, water buffalo, and long-horned cattle during its wetter prehistoric phases. Oil exploration transformed the region economically; the Shaybah oil field was discovered in 1968, and South Ghawar, the world's largest oil field, extends into the northernmost sections of the Rub' al Khali.
A road connecting Oman and Saudi Arabia through the Empty Quarter was completed in September 2021, measuring between 700 and 800 kilometres and running from Ibri in Oman to Al-Ahsa in eastern Saudi Arabia. Prior to this, the interior of the Rub' al Khali had no paved road connections, and movement through it required specialist desert navigation and extensive logistical support — conditions that mirror the challenge faced by Dakar Rally competitors crossing its dune systems during each January edition.