Rub' al Khali

The Rub' al Khali is a massive desert on the Arabian Peninsula. Many people call it the Empty Quarter.

It covers a huge part of the southern third of the peninsula. The desert spans parts of Saudi Arabia, Oman, the United Arab Emirates, and Yemen. It is a major part of the larger Arabian Desert. This region is defined by its vast scale and extreme environment.

The terrain is mostly made of ergs, which are large areas of sand dunes. These dunes can reach heights of 250 meters. The sand has a reddish-orange color because of a mineral called feldspar. Between the dunes, you will find plains of gravel and gypsum. There are also brackish salt flats, known as sabkhas, on the eastern edge. Some researchers, like Ali Al-Naimi, suggest the dunes do not drift much. They believe moisture from the sabkhas leaches into the base of the dunes. This moisture likely keeps the essential shape of the dunes intact.

Thousands of years ago, the desert was much wetter. Between 6,000 and 2,000 years ago, shallow lakes existed in the middle of the desert. These lakes likely formed from cataclysmic rainfall similar to modern monsoons. Most of these lakes probably lasted only a few years. However, in the Mundafen area, lakes lasted up to 800 years. This happened because of increased runoff from the Tuwaiq Escarpment. These water sources supported a wide variety of life.

Fossil evidence shows that many animals once lived in these lake beds. Scientists have found remains of hippopotamus, water buffalo, and long-horned cattle. Small creatures like snails, ostracods, and freshwater clams also lived there. The presence of plants and algae is proven by calcium carbonate and opal phytoliths. Humans also left traces of activity between 3,000 and 2,000 years ago. While people left chipped flint tools, no human remains have been found. This shows the desert has changed significantly over millennia.

Today, the climate is classified as hyper-arid. This means the environment is extremely dry. Annual precipitation is generally less than 100 mm. Humidity also changes drastically with the seasons. It averages about 52% in January but drops to 15% in June and July. The fauna includes rodents and arachnids, such as scorpions. The dromedary, or Arabian camel, is a very important animal here. In Oman, the black camel is a rare and prized breed. The Asiatic cheetah was once in Saudi Arabia but is now extirpated.

Resources and trade have shaped the history of the region. Long ago, caravans carried frankincense across the land. This trade continued until about 300 AD before desertification made the paths difficult. Some believe the lost city of Ubar or Iram relied on this trade. Archaeological remains of Iram include walls and circular pillar bases. In the modern era, the desert became vital for energy. The South Ghawar oil field was discovered in 1948. It is the largest oil field in the world. The Shaybah oil field was also discovered in 1968.

Many explorers have attempted to cross this difficult landscape. British explorers Bertram Thomas and St John Philby made journeys in the 1930s. Wilfred Thesiger mapped large parts of the area between 1946 and 1950. In 1950, a US Air Force expedition used trucks to collect specimens. More recently, Jamie Clarke crossed the desert in 1999 using a camel caravan.

In 2025, Gavin Booth and Adam Wilton completed a self-sufficient foot crossing. They hauled all their own supplies in custom-built carts. These expeditions help scientists understand this unique part of our world.