Which Countries Have the Most Desert? How the Ranking Has Changed Since 1990

Of all the countries whose land averages less than 250 mm of rain a year, the usual threshold for a desert, the largest are Algeria (2.38 million km² of land, 89 mm a year), Saudi Arabia (2.15 million km², 59 mm) and Libya (1.76 million km², 56 mm), according to World Bank data for 2022. Iran, Mongolia, Niger, Mauritania, Egypt, Yemen and Turkmenistan complete the top 10. China has the largest total area of desert of any country, but because its wet south and east lift its national average to 645 mm, it is a country with big deserts rather than a desert country.

“Most deserts” is a slippery idea, so this ranking uses a measure with one source and a clear rule. The World Bank publishes each country’s long-term average precipitation, taken from the UN Food and Agriculture Organization, alongside its land area. A country whose average falls below 250 mm is, taken as a whole, a desert; the table ranks those countries by land area. The interesting part is how that list has changed over the past 30 years, because almost none of the change came from the weather.

The 2022 World Bank table: ten countries under 250 mm

Kazakhstan and Sudan: 4.6 million km² sitting on the 250 mm line

Egypt is the driest of the ten, averaging just 18 mm a year; Mongolia, at 241 mm, only just qualifies. Two large countries sit exactly on the line. Kazakhstan, with 2.7 million km² of land, and Sudan, with 1.87 million km², both average 250 mm, so under a rule of “250 mm or less” they would rank first and fourth. Uzbekistan (206 mm), Iraq (216 mm) and Oman (125 mm) follow just below Turkmenistan.

The precipitation figures are long-term averages, so they barely move from one edition to the next: Algeria’s 89 mm and Libya’s 56 mm are the same in the 2022 data as in the earliest the World Bank reports. What has changed is the map. Since 1990, new borders have added Yemen and Turkmenistan to the top 10, put Uzbekistan just outside it and left Sudan sitting exactly on the line. Changes on the ground, meanwhile, have happened in places the averages cannot see.

1990 to 1992: Yemen unites and the Soviet Union breaks up

In 1990 the table would have looked different at the bottom. On 22 May 1990 North Yemen and South Yemen merged to form the Republic of Yemen, creating a single country of about 528,000 km² whose average rainfall of 167 mm places it ninth. The two halves had separate histories: North Yemen became an independent kingdom in 1918 as the Ottoman Empire dissolved, while most of South Yemen had been the British Aden Protectorate.

A year later the collapse of the Soviet Union did something larger. Until 1991 the Karakum and Kyzylkum deserts of Central Asia were part of the world’s biggest country, whose national average, dominated by Siberia and European Russia, was nowhere near desert levels. When Turkmenistan and Uzbekistan became independent, their data begin in 1992, and both are deserts on average. The Karakum, whose name means “Black Sand”, covers about 350,000 km², roughly 70 per cent of Turkmenistan, with rainfall of 70 to 150 mm a year and on average one person for every 6.5 km². The Kyzylkum, or “Red Sand”, covers about 298,000 km² divided among Kazakhstan, Turkmenistan and Uzbekistan; Uzbekistan, with 206 mm and 440,652 km² now sits 11th.

The Soviet period left its mark on both. The Karakum Canal, built between 1954 and 1958, carries about 13 km³ of water a year from the Amu Darya for 1,375 km across the desert to the cotton oases of Mary and Tejen. That diversion, and others like it on the Syr Darya, set off the fastest change on this whole list.

The Aral Sea since 1960: the Aralkum, a desert born within a lifetime

In 1960 the Aral Sea, shared by Kazakhstan and Uzbekistan, was one of the four largest lakes in the world at about 68,000 km². Once Soviet irrigation schemes diverted the rivers that fed it, it began to shrink, and by 2007 it had fallen to 10 per cent of its original size, splitting into separate northern and southern basins and smaller lakes. The exposed seabed is now the Aralkum Desert, the youngest desert in the world, lying south and east of what remains of the eastern basin.

The sea had supplied up to one-sixth of the Soviet Union’s fish; today rusting trawlers sit in the sand at the former port of Moynaq. The two countries have taken different paths since. Kazakhstan completed the Dike Kokaral in 2005 to hold water in the northern basin, and by 2008 its level had risen 12 m from 2003, bringing back enough fish for some fishing. The southern basin, mostly in Uzbekistan, kept falling; its eastern lobe dried up completely in 2009 and has since been only occasionally and slightly replenished. The Aralkum does not change the World Bank table, because averages of rainfall ignore what happens to a lake, but it is the clearest case of a country gaining desert in the past 60 years. You can follow the whole story in our article on the Aral Sea.

2011: South Sudan’s independence and the new largest country in Africa

Until 2011 Sudan was the largest country in Africa. It stretched from the Sahara on the Egyptian border to the wet savannas and swamps of the upper Nile, so its national average rainfall was far higher than that of the Sudan left today. On 9 July 2011, after 98.8 per cent of southern voters backed independence in a January referendum, South Sudan became a separate state. Algeria became Africa’s largest country, a title it still holds with 2,381,741 km².

The Sudan that remained is much drier. Its World Bank precipitation series begins in 2012, at exactly 250 mm. That places a country of 1.87 million km² precisely on the border of the desert definition, which is why it appears as a near-miss rather than a member of the table. In practical terms, most of northern Sudan is the eastern Sahara, part of an area of about 1 million km² across Libya, Egypt and Sudan where the long-term mean rainfall is around 0.5 mm a year.

China and Mongolia since 1978: fighting the Gobi’s southern edge

Mongolia, fifth in the table at 241 mm, shares the Gobi with China. The Gobi covers about 1,295,000 km² and has been spreading southward into China, where around 3,600 km² of grassland a year was being overtaken, according to a 2016 New York Times report. Dust storms became more frequent between 1996 and 2016, and overgrazing, deforestation and water extraction are blamed alongside climate change. In Mongolia about 90 per cent of the land is fragile dryland, pushing many herders into the cities.

China’s response began in 1978 with the Three-North Shelter Forest Program, a belt of planted windbreaks meant to run until 2050, often called the Great Green Wall. In November 2024 the government reported that the 3,000 km green belt around the Taklamakan Desert, 46 years in the making, was complete. The official share of China covered by desert fell from 27.2 per cent a decade earlier to 26.8 per cent in 2024. Applied to China’s 9.6 million km², 26.8 per cent is still about 2.6 million km² of desert, more than all of Algeria.

Local projects show the same shift. In the Kubuqi Desert of the Ordos Basin, a company and the government began restoring vegetation in 1988, and by 2017 about a third of the desert had been greened; solar panels installed since then cut wind speed and keep the ground beneath them moist. None of this moves China into or out of the table, but it is the main place where desert area has measurably shrunk over the past decade.

Niger and Mauritania: the Sahel’s dry decades

Niger (151 mm) and Mauritania (92 mm), sixth and seventh, both run south from the Sahara into the Sahel, the semi-arid belt that stretches 5,900 km from the Atlantic to the Red Sea. Here the change of the past half-century has been in rainfall itself. Annual rain across the Sahel fell by 20 to 40 per cent between the periods 1931–1960 and 1968–1990, and between 1951 and 2004 the region had some of the most consistent and severe droughts in Africa. Rainfall recovered slightly in the mid-1990s in some central and eastern areas. The 2010 drought showed how thin the margins remain: in June of that year Bilma in Niger set a national temperature record, and 350,000 people in Niger faced starvation.

Because the World Bank uses long-term averages, those swings do not reshuffle the table, and no country has dropped off it through rain alone in the past 30 years. The ranking has moved at its edges through politics: a unification in 1990, a break-up in 1991 and a partition in 2011. For the countries that receive the least rain of all, measured without regard to size, see our list of the driest countries in the world, and for the desert that covers most of the top three, our guide to the Sahara.