It comprises a vast plain of sand stretching from northeastern Niger to western Chad, occupying an area of over 400,000 square kilometres (150,000 sq mi).

According to a NASA study, the sunniest spot in the world would be a ruined fort in Agadem in the southeastern Ténéré, and has even clearer skies than the polar deserts overall.

In the north, the Ténéré is a vast sand sheet - the true, featureless 'Ténéré' of legend reaching up to the low hills of the Tassili du Hoggar along the Algerian border.

In the centre, the Bilma Erg forms rows of easily navigable low dunes whose corridors make regular byways for the azalai or salt caravans.

They hunted wild animals and left evidence of their presence in the form of stone tools including tiny, finely carved arrow heads.

During the Neolithic period about 10,000 years ago, ancient hunters, the early Holocene Kiffian people, created rock engravings and cave paintings that can still be found across the region.

Several archaeological sites that date from this time, often identified as part of the Tenerian culture, are dotted across the deserts along the borders of Niger, Algeria and Libya.

While the well-known Tuareg occupy the Aïr Mountains and Agadez to the west, and still operate the salt caravans for Hausa merchants, other inhabitants of the Ténéré, found from oases like Fachi eastwards, are the non-Berber Kanuri and Toubou.

Situated by the last well before entering the Grand Erg du Bilma on the way to Fachi, salt caravans relied on the tree as a landmark until it was allegedly knocked down by a truck driver in 1973.

A monument to UTA Flight 772, a 200-foot diameter circle of dark stones and 170 broken mirrors which represent each victim of the 1989 terrorist attack which brought down the aircraft, was built in May and June 2007 at 16°51′53″N 11°57′13″E.