The Arabian Desert covers almost the whole Arabian Peninsula, about 2.33 million km², stretching from Yemen to the Persian Gulf and from Oman north into Jordan and Iraq; most of it lies in Saudi Arabia. It is the largest desert in Asia and the fourth largest in the world. It is not one sea of sand but a set of distinct regions: the Rub’ al Khali (Empty Quarter) in the south, the Nafud in the north, the long sand bow of the Dahna between them, the Hejaz and Asir mountains along the Red Sea, gravel and lava plains, and salt flats on the Gulf coast. Most of it gets about 100 mm of rain a year, summer highs in the lowlands top 40 °C, and beneath its eastern edge lies Ghawar, the world’s largest conventional oil field.
The Empty Quarter’s 250-Metre Dunes
Most of the peninsula’s southern third belongs to the Rub’ al Khali, which spreads across Saudi Arabia, Oman, the United Arab Emirates and Yemen. Its 650,000 km² run roughly 1,000 km from end to end and 500 km across, making it the largest continuous body of sand in the world. Its surface slopes from about 800 m in the south-west to near sea level in the north-east. Most of it is erg, or sand sea, where dunes climb as high as 250 m above flat floors of gravel and gypsum. The sand is 80 to 90% quartz; the rest is feldspar, whose iron-oxide coating colours the dunes orange, red and purple.
It is hyper-arid, with generally less than 50 mm of rain a year, and relative humidity averages about 15% in June and July. The Empty Quarter was once wetter. Hardened beds of carbonate, gypsum and marl along the middle of the desert mark shallow lakes that existed 6,000 to 5,000 years ago and again 3,000 to 2,000 years ago, and fossils show hippopotamus, water buffalo and long-horned cattle once drank there. Today only 37 plant species are recorded in the Rub’ al Khali. The first documented journeys by outside explorers were made by Bertram Thomas and St John Philby in the early 1930s; Wilfred Thesiger crossed it several times between 1946 and 1950 and described it in Arabian Sands (1959). A paved road through it, from Ibri in Oman to Al-Ahsa in Saudi Arabia, was completed in September 2021. Our guide to the Rub’ al Khali goes into the Empty Quarter in more detail.
The Nafud’s Red Dunes in the North
In north-central Saudi Arabia the Nafud fills an oval depression about 290 km long and 225 km wide, covering 65,000 km². It is an erg of brick-red sand, shaped by sudden violent winds into large crescent dunes, and it sees rain only once or twice a year. In lowlands near the Hejaz Mountains, oases grow dates, barley, vegetables and fruit.
The Nafud’s human story runs deep. In 2016 Mathieu Duval of Griffith University found an 85,000-year-old fossil human finger bone in the Nafud, which has been described as the earliest evidence of modern humans outside Africa and the Levant. During the Arab Revolt of 1917, Auda abu Tayi’s force skirted the edge of the Nafud on its way to Aqaba, though, unlike in the film Lawrence of Arabia, it did not cross it.
Ad-Dahna, the 1,000 km Sand Bow
A narrow corridor of sand links the two great sand seas. The Ad-Dahna curves in a bow for more than 1,000 km from the Nafud in the north to the Rub’ al Khali in the south-east, yet is no more than about 80 km wide. It is made of seven successive belts of high, mostly red dunes, separated by plains, and it forms the boundary between the Najd plateau of central Arabia and the Al-Ahsa region in the east. Roads cross it to link Riyadh with Kuwait and with Al-Ahsa.
Just east of the Dahna, the limestone Summan plateau is riddled with caves, known locally as dahls, with stalactites and passages several kilometres long. Bedouin used some as water sources long before the first systematic study of them in 1981.
Hejaz and Asir: The Mountain Wall on the Red Sea
Along the western edge of the peninsula the desert ends at a wall of mountains. The Sarawat range runs parallel to the Red Sea from the Hejaz in the north through Asir to Yemen. The mountains belong to the Arabian Shield and are made up mostly of volcanic rock; their western slopes drop steeply to the coastal plain of the Tihamah, while the eastern slopes descend gently towards the interior, cut by wadis. The name Hejaz comes from the Arabic root meaning “to separate”, because the region divides the Najd from the Tihamah.
The highest ground is in the south. Jabal An-Nabi Shu’ayb near Sana’a in Yemen, at 3,666 m, is the highest peak in Arabia, and every Sarawat summit above 3,000 m lies in Yemen. In Saudi Arabia, Jabal Sawda in Asir is officially the highest point at 3,015 m, although surveyors in 2018 put it at 2,999 m, a little below nearby Jabal Ferwa. Spread over roughly 100,000 km², the Asir range catches seasonal rain of 600 mm a year, rising past 1,000 mm in its wettest spots, the most anywhere in the kingdom. Farmers grow wheat, coffee and vegetables on terraced slopes, and Asir is thought to be one of the last refuges of the Arabian leopard. Rain falls off sharply to the east, to below 100 mm on the interior plateaus.
Gravel Plains, Lava Harrats and the Tuwaiq Escarpment
Between the mountains and the sand seas, much of the desert is not dunes at all but stony ground. The Tuwaiq escarpment curves for about 800 km through central Arabia as a line of limestone cliffs, plateaus and canyons, just west of the Dahna. Elsewhere the rock surface is volcanic. Lava fields, called harrat, cover large areas in the west and north. Harrat Rahat, the largest in Saudi Arabia, last erupted in 1256, when a lava flow travelled 23 km and stopped within 4 km of Medina. On the border with Jordan and Iraq, the Harrat al-Harrah Reserve, set up in 1987, protects 12,150 km² of black basalt boulders and extinct cones in the Harrat al-Sham.
Sabkhas from Abu Dhabi to Umm al Samim
Along the southern shore of the Persian Gulf, the desert meets the sea in sabkhas: flat coastal salt plains just above high tide, where groundwater rises and evaporates, leaving crusts of gypsum and salt. The coast of the United Arab Emirates is the textbook example geologists use to define the landform. Near Abu Dhabi the salt flats cover about 36,000 km². Rainfall there averages only about 40 mm a year, the water table is never more than 1.5 m down, and the strong north-westerly shamal can drive seawater up to 5 km inland across the flats.
Inland sabkhas can be dangerous. Umm al Samim, on the eastern edge of the Rub’ al Khali, mostly within Oman, is a closed basin where water from the Omani mountains and desert wadis drains and evaporates. Its solid-looking crust hides quicksand, and local names for it translate as “Mother of Poisons”. Thesiger, in the late 1940s, was the first European to see it.
Wadi al-Rummah and the Al-Ahsa Oasis
The desert has no permanent rivers, only wadis that flow after rain. The largest, Wadi al-Rummah, runs for almost 600 km north-east from near Medina and carries water for an estimated 60 days a year, supporting the farms of Al-Qassim, before it disappears into the Dahna dunes near Buraidah. On the far side of the sand it re-emerges as Wadi al-Batin, which forms the western border of Kuwait and reaches the Gulf. Abdullah Al-Musnad of Qassim University has suggested that about 10,000 years ago it was a single perennial river some 1,200 km long.
Groundwater, not rivers, sustains the great oases. Al-Ahsa, about 60 km inland from the Gulf coast in eastern Saudi Arabia, is fed by a large aquifer and more than 280 artesian springs. It holds more than 2.5 million palm trees, mostly date palms, around the cities of Al-Hofuf and Al-Mubarraz, and became a UNESCO World Heritage Site in 2018. Its name refers to sand lying over an impermeable layer that traps rainwater beneath it.
From the Arabian Oryx to the Oil Under Ghawar
The Arabian Desert supports about 900 plant species, 102 native mammals and some 310 bird species, including the sand gazelle, Nubian ibex, Arabian wolf, caracal and sand cat. The Asiatic cheetah and Asiatic lion once lived here and are gone. The best-known survivor is the Arabian oryx. Hunting parties with cars and rifles, some of them reported to use as many as 300 vehicles, wiped out the wild population: the last wild oryx before reintroduction was reported in 1972. A captive herd started at the Phoenix Zoo in 1962 with nine animals, and releases into the wild began in Oman in 1980.
In 2011 it became the first animal to move from extinct in the wild to vulnerable on the IUCN Red List, and in 2016 about 1,220 lived in the wild. Saudi Arabia’s only wild herd lives in the 12,000 km² Uruq Bani Ma’arid Reserve, where oryx were released between 1995 and 2013 and which became the country’s first natural World Heritage Site in 2023. Not every project worked: in June 2007 Oman’s Arabian Oryx Sanctuary became the first site ever removed from the World Heritage List, after Oman cut the sanctuary by 90% once oil was found there and its herd fell from 450 in 1996 to 65.
Oil is the desert’s other defining resource. Ghawar, in Saudi Arabia’s Al-Ahsa Governorate, measures about 280 by 30 km and was discovered in 1948 after geologists noticed a bend in the dry Wadi Al-Sahbah that hinted at uplift. Its oil sits in Jurassic Arab-D limestone 1,800 to 2,100 m below the surface; Saudi Aramco’s 2019 bond prospectus gave its maximum output as 3.8 million barrels a day, and it had produced roughly a third of the kingdom’s cumulative oil by 2018. The Shaybah field, found in 1968, lies in the Empty Quarter itself. The kingdom’s wider reserves are covered in our guide to the natural resources of Saudi Arabia, and the Sahara and Arabian deserts compared sets this desert against its larger neighbour across the Red Sea.