Beyond the Siwa depression are five smaller oases, visited by relatively few tourists. Qara, far away on the edge of the Qattara Depression, makes a rewarding day-trip, while travellers bound for Bahariya can see something of Areg and Nuwamisa, if not the more secluded oases of Bahrein or Sitra.

Qara Oasis

If you’re seriously into desert travel, Qara Oasis (often pronounced “Gara” or “Djara”) has a compelling fascination. The only inhabited oasis beyond the limits of the Siwa depression, it has been aptly called “Siwa yesterday” due to its isolation. Qarawis still live entirely from their palm groves and vegetable plots, irrigated by seventeen wells. Legend has it that these could only sustain 314 people, so whenever a child was born, an elder would have to leave the oasis.

Until flooding rendered it unsafe in 1982, the Qarawis occupied a Shali-like fortress atop “a solitary white mushroom of rock”, edged by a “high smooth wall, impregnable to raiders, with one black tunnel for a street”, as the explorer Bagnold saw it in the 1920s. Now, most families live in new stone houses on the plain. People trace their ancestry from the Hamudat tribe, a mixture of Bedouin, Berbers and Sudanese (some of them runaway slaves).

Visitors are so rare that the villagers turn out to welcome them and serve a meal in their honour. Qarawis speak Berber among themselves, but Arabic is widely understood.

Qattara Depression

Beyond Qara the land plummets into the Qattara Depression, which is seven times the size of all the Western Desert oases combined and, at its lowest point (141m below sea level), the deepest depression in Africa. The salt marshes and lakes at the foot of the northern escarpment were regarded as an impenetrable obstacle to Rommel’s Panzers during the Battle of El-Alamein.

Planners have long dreamed of piping water 38km from the Mediterranean to the depression, utilizing the fall in height to generate hydroelectricity and run desalination plants and irrigation systems, but all attempts have foundered through lack of capital. There is, however, exploration for oil at many points in the desert between Qattara and Mersa Matrouh, with upgraded tracks identified by the logos of oil companies. Local Bedouin are bitter that World War II minefields have only been cleared to allow drilling, while their ancestral grazing grounds remain hazardous to enter.

Siwa to Bahariya

Following the ancient Darb Siwa caravan trail, the 420km road (tarmackd for 250km) from Siwa to Bahariya takes four to six hours to drive and has six checkpoints which provide assurance that vehicles which break down will be missed, but otherwise there are no sources of water, nor any fuel – and mobile phones are beyond signal range. Safari operators charge £E1500 for up to four people to travel to Bahariya; £E2000 with one or two stopovers en route; or £E2500–2800 to carry on to the White Desert and camp there. Cars must travel in convoy leaving the Carpet Factory at 7am, while travel permits and an army guide with a satellite-phone are mandatory

Areg Oasis

Easily reached on foot from the road, Areg Oasis (pronounced “Arej”) is surrounded by striated chalk buttes which look like giant brioches that have sat in the oven too long. Regarded as a haunt of bandits by nineteenth-century travellers, its cliffs are riddled with scores of tombs. A tablet from Alexandria records that the population of Siwa, Bahrein and other now-deserted oases numbered four hundred thousand in Persian times.

Bahrein Oasis

Ten kilometres off the road, Bahrein Oasis – named after its two azure salt lakes – is awash with custard-coloured sand, hemmed in by croissant-shaped buttes riddled with Greco-Roman tombs. Seductive as they look, the salt lakes are surrounded by mushy sand and salt crusts that can trap unwary vehicles, and if safari groups camp here they do so in the palm groves on the far side, away from the mosquitoes and protected from sandstorms.

Nuwamisa and Sitra oases

Nuwamisa Oasis, roughly 3km off the road from Siwa to Bahariya, looks equally lovely, with a salt lake rimmed by palms and crescent cliffs – but its name, “Oasis of the Mosquitoes”, is all too true. Millions of mosquitoes swarm as soon as the sun goes down, making camping a nightmare even if you’re all zipped up in your tent.

Safari groups prefer to camp in Sitra Oasis, 15km away, which isn’t so badly infested. Traditionally a watering hole for Bedouin smugglers bringing hashish into Egypt, it is still sometimes used as a fuel-cache by motorized traffickers in various contraband.

For the final 45km of the journey to Bahariya the road skirts the whale-backed Ghard Kebir (Great Dunes), voyaging south from the Qattara Depression and destined to arrive in Bahariya in a few hundred years.