More than two-thirds​ of the Earth’s surface is covered in sea water. The gigantic archipelagos we call continents consist of 33 per cent desert, 25 per cent mountain and 30 per cent forest. The forested area has been much reduced over the last two thousand years, and in a matter of decades we have shown ourselves capable of melting polar and alpine glaciers and destroying marine ecologies. But deserts don’t seem to be susceptible to humans’ dubious achievements. Desert won’t vanish under the pressure of human activity; on the contrary, what frightens us is that it will advance. The UN Convention to Combat Desertification came into force in 1996. In 2024 it reported that more than three-quarters of the world’s land ‘has become permanently drier’ since the convention was signed. Much of this expansion is in what the UN calls ‘drylands’, not all of which are desert. But it estimates that the Sahara – the desert par excellence – has claimed around an extra million square kilometres over the last century, inching relentlessly southward into the dry savannah of the Sahel. At more than nine million square kilometres, it is now nearly the size of Europe.

Judith Scheele is cynical about desertification and uses the word with scare quotes. To her mind, it is a concept inherited from European empires by international bodies and NGOs, reducing the Sahara to a problem to be solved and subjecting those who live in and around it to what are effectively colonial agendas. She’s irked by the outsider’s view of the Sahara as a hostile world, either populated by wildlings or empty of life. Arab geographers ‘were almost exclusively interested in supply points and “civilisation”’ on the routes across the Sahara, she writes, not in the people who hovered in the distance, unless they threatened to disrupt trade. Scheele doesn’t think that trans-Saharan trade routes really existed – they shifted too often. Early Western geographers populated the desert with imagined creatures, but ‘by the 19th century, colonial maps … mostly showed nothing … The idea of the Sahara as an essentially empty space had found its perfect visual expression.’ Eugène Fromentin wrote in Sahara et Sahel (1887) that ‘vast populations inhabit this immense expanse … which it would be a great mistake to regard as empty, and where people had nevertheless imagined all manner of chimerical beings, except for man, the most real and the most numerous of them all.’

The question of who these people are is central for Scheele. The answer given by French colonisers was racial: Saharans are white. The great colonial geographer of the Sahara, Émile-Félix Gautier, author of a dozen books on the subject, including L’Afrique blanche (1939), characterised the desert, in a bestseller published in 1928, as an environment essentially suited to the ‘white race’, on account of its low temperatures. He noted that these freezing conditions were ‘in some measure responsible for the fact that, in the diffusion of the human species, the Sahara has become the home of a white race’. Gautier’s notion took hold, at least in francophone Africa. It might seem logical, at least as a way of marking off the Sahara from ‘Black Africa’ – an expression whose peculiarity only really struck me after a Moroccan colleague used it, in English, in a lecture to students in Florida and received a response that shook him. Scheele dislikes the expression too, though not for the reasons it played badly in a US lecture theatre, where students could not imagine a white Africa. Scheele rejects the notion of a racial divide as an artificial distinction, imposed by colonial discourse.

In her view the ‘classification’ casts North Africa as an ‘accidental appendage’ of the African continent, whose Arab inhabitants would never be quite African enough, even though many Muslim Africans across the continent use the Arabic language. It also obscures the fact that Black people form a majority in the Sahara, and makes the significant Black minority in North African countries ‘strangers in their own land’. Yet Scheele knows that the standard version of Arabic used for religious and intellectual purposes in North Africa is not the same as the language spoken in everyday life, and that Black people in North Africa, the majority of them descendants of the enslaved, can indeed feel like foreigners in their own countries, or at the very least like second-class citizens and objects of racism.

Even if Scheele deplores it, this racial classification is older than colonisation. In the eighth century, Arab geographers gave the name Bilād as-Sūdān, ‘the land of the Blacks’, to the region immediately south of the desert, which we now call the Sahel. The peoples of the Sahel regarded Arabs and Berbers as whites. In Gao and Kano, the main southern terminus points of trans-Saharan trade, there was an official known as korey-farma in Songhay or sarkin turawa in Hausa: both terms translate literally as ‘chief of the whites’ – the person responsible for dealing with Arab-Berber merchants and visitors. Much earlier, Greco-Roman geographers referred to all of sub-Saharan Africa as ‘Ethiopia’, or the land of people with ‘sunburned faces’. The poem ‘Moretum’, once attributed to Virgil, features an African servant with ‘hair tightly curled, lips thick, colour dark’. In Alexandria, in the second century ce, Ptolemy synthesised the research of his colleagues and reports from merchants to imagine a central Sahara – he calls it Inner Libya – whose population was a mixture of white and black. In his stab at physical anthropology, the Sahara was inhabited by tribes of Blacks with white people’s features, the Melanogaetuli, and whites with Black people’s features, the Leukaethiopes. The Libyoaethiopes, Black Saharans, were mentioned later by Orosius.

For contemporary Western media, this motley Sahara does not exist: it’s simply the land of the Tuareg, the ‘blue men of the desert’, light-skinned, perched on camels and dressed in dark blue robes, peering through the slits in the lithams that cover their mouth and head, and often fighting for their freedom against states in the Sahel. Scheele doesn’t resist the charismatic image of the Tuareg rebel, which she evokes in her discussion of the Tuareg band Tinariwen (‘deserts’ in Tamasheq, the Tuareg language). The band members met in an Algerian refugee camp, then moved to Libya, before returning to Mali

when the second Tuareg rebellion against the Malian central government broke out in 1990. This was when they crafted their legendary style: young men with wild hairstyles, what was left of their turbans wrapped loosely around their necks; an electric guitar over one shoulder, an AK-47 over the other; traces of mud – or is it blood? – on their faces.

Scheele writes that Tinariwen rebelled against ‘an authoritarian nation-state and its military organs’, even though the Tuareg kept up hostilities for several years after the military regime in Bamako was toppled in 1991 and the country became a democracy – as it remained until recently. Her aim is to challenge ‘two millennia’ of preconceptions about ‘the Sahara, its people, its history, even its geography’, but positioning the Tuareg the way she does suggests that she, too, has preconceptions: that there really are ‘Saharans’ and that the Tuareg are the chief example.

Scheele’s desert peoples are those of the central Sahara: northern Chad and Mali, Libya, Algeria – countries she knows well. This is the land of the Tuareg and the Tubu (and others). But even here, there is a world of difference between the ‘Moors’ of Mauritania – a term that’s lost currency among scholars, though not on the ground – and the Arabs of Sudan. What remains is the idea of a Saharan way of life. It consists, on the one hand, of adaptation to the desert environment – which Scheele describes well, and which could just as easily apply to the inhabitants of the Arabian desert – and, on the other, of the multiple interactions between the peoples of the Mediterranean and the Sahel. As the desert advances, aspects of this way of life shift southwards, along with its inhabitants. Tea slowly boiled on embers, a Tuareg speciality, has turned into a Sahelian tradition; turbans have become more widespread with the proliferation of dust storms; the Tuareg are becoming part of the fabric of life in western Sudan. This is less striking than Tuareg rebellions, but more significant in the long run.

The term ‘Sahara’ is from the Arabic – it means ‘the ochre lands’. (Seeing the Sahara for the first time, Fromentin described a world that was ‘neither red, nor wholly yellow, nor tawny, but precisely the colour of a lion’s skin’.) Peninsular Arabs were already using the word for their own deserts when their armies entered Egypt in 639 ce and described what they saw as As-Sahra al-Kubra, ‘the larger ochre lands’. Clearly, they were better equipped to invade where the Romans failed – or didn’t try. The Sahara forms part of a discontinuous belt of deserts that stretches from the Atlantic to western China. It is broken by river plains and mountain ranges but is so distinctive that geographers refer to it as the ‘arid diagonal’. The deserts in the south-western part of the diagonal – those of the Sahara, Western Asia and Arabia – are not only dry but torrid. Cut off from two major sources of precipitation, the polar front and the westward-flowing equatorial currents carried by the trade winds, they are lands of perpetual aridity. Only Yemen and parts of Oman in the Arabian Peninsula are touched by the monsoon winds of the Indian Ocean: they were known by ancient geographers as Arabia Felix. These arid landscapes are varied: between the vast rocky plateaus, lateritic trenches, flat stretches of pebbles and gravel there are fossil valleys and depressions of baked mud left by vanished lakes. There are seasonal streams: the gorges of some mountain ranges are well watered and suitable for limited cultivation. But the most recognisable feature of this environment, though not the most common, is the erg – a mesmerising expanse of sand dunes that makes up 15 per cent of the Sahara.

All these deserts, African as well as Arabian, were an immense savannah until six or seven millennia ago, and may return to that state, but recorded history began at a moment when they were formidably dry, at one extreme in their long sequences of desiccation and renewal. That moment in the cycle was set off by a tilt – or rather a slight wobble – in the Earth’s axis, a phenomenon that occurs regularly in Milankovitch cycles, which describe variations in the planet’s orbit over tens of millennia. The event weakened West African monsoons and shifted the continental interior of North Africa and the Middle East away from rainy weather systems. The savannah that vanished as a result must have resembled what remains further south, in the Sahel, or better, in the more humid Sudanic climatic zone. There were patches of arid land, but mostly there were vast grasslands and woodlands through which rivers coursed. Lake Chad was larger than the Caspian Sea.

Medieval West Africans prized the Sahara’s copper and salt, and while the outside world was drawn to its gold, the empires of the Sahel took more income from internal trade in all three commodities. In the years following decolonisation, the French found reserves of oil and gas in the Algerian Sahara and uranium in Niger’s Ténéré Desert. Algeria has turned into a militarised petrostate that has given up agriculture – in particular the vineyards left by the French – in exchange for oil rents; and while Scheele lambasts the French for the pollution caused by uranium extraction, many Nigeriens dream of the money it would bring. But the Sahara’s most intriguing resource is water and Scheele’s account of it is gripping.

The mega-lake in Chad is gone, but the mineral depths of the Sahara are full of large bodies of water. They are not really replenished, though rains in the south feed them to some degree. One of these fossil lakes, the largest in the world, is equivalent to two-thirds of the surface area of the Mediterranean. Known drably as the Nubian Sandstone Aquifer System (NSAS), it lies beneath northern Chad, northern Sudan, south-east Libya and southern Egypt. Almost three-quarters of the fresh water used in Libya is pumped from NSAS and piped thousands of kilometres north to supply the coastal cities. Oil was discovered in Arabia by American geologists who were looking for fossil water; fossil water in Libya was found by oil companies drilling for oil. NSAS has a counterpart in the central Maghreb, the North-Western Sahara Aquifer System (NWSAS), which has been exploited for longer and supplies southern Algeria, Tunisia and Libya. Smaller underground water sources, barely exploited, dot the countries of the Sahel. Intensive exploitation in one place has repercussions elsewhere. There is no international regime regulating use and misuse: ‘for now,’ Scheele writes, it is ‘take what you can for as long as you can.’

The careful use of water in oases, necessary before the exploitation of underground aquifers, relied on methods refined over the centuries. In her unromantic account of oasis management, Scheele dispenses with the picture of a paradise of palm trees, gurgling water and cool shade in the fiery desert. In the images used for screensavers or soft drinks labels, she remarks, humans are mostly absent, though people have always been indispensable for the survival of oases. They are difficult ecologies to manage and so tended to have sturdy governance systems that ensured the just and sustainable use of water. The labourers on which oases depended were often slaves and subalterns. Most oasis-dwellers were poor; many foods had to be imported and the threat of marauding nomads was ever present. But these artificial paradises were places of respite for exhausted travellers, developing along trade and pilgrimage routes. Other deserts, like the Kalahari, have no oases – proof that the oasis is anything but natural.

The Sahara is now one of the most inhospitable places on earth, but not because of the desert. It is a dumping ground in which distant powers and states jettison their problems. Algeria has pushed its Islamist militants south, to the detriment of the Sahelian countries; Europe drives migrants back into the desert by bribing North African states; the Emirates conduct political and military business in the eastern reaches of the desert; the juntas in Mali and Niger have ended the policy of engagement with Saharan communities, exacerbating the jihadist crisis in the region. ‘Terrorism’ does not begin to describe the sense of generalised insecurity and imminent threat from various armed groups.

Last June, in Genoa, I spoke to Pier Luigi Maccalli, an Italian priest who was kidnapped by jihadists in September 2018 in a village near Niamey, the capital of Niger. He was taken at least a thousand kilometres north into the heart of the desert, where he was held for two years. Like Scheele, he was at a loss to describe what seems to be happening in the Sahara. Nothing during his time in Africa had prepared him for the brutality he endured at the hands of young men whose Islamic education should have taught them respect for elders, strangers and clerics. Maccalli’s account of his captivity, Chaînes de liberté: Prisonnier au Sahel (2022), reads like an anthropologist’s monograph. It also echoes the story of the Scottish explorer Mungo Park, captured by Moors in the late 1790s and held in Benowm, not far from where Maccalli ended up. Park, though subjected to the same insults reserved for infidels, was not tied to a stake, as Maccalli was. Instead, his captors tethered a hog beside him – a suitable companion, they thought. At the moment of his release, Maccalli offered his hand to his captors; it was refused. Park managed to escape, as did one of Maccalli’s fellow captives.

Many of the dangers that Saharans and Sahelians faced two or three centuries ago have re-emerged. Scheele is tired of Western tropes and clichés about the region. She is particularly scathing about French domination, but as an anthropologist she may be among the last exponents of a discipline that colonialism enabled and which has now become next to impossible.