Many valleys of Aïr or Ásben[133] might produce much more than they do at present; but as almost the whole supply of provision is imported, as well as all the clothing-material, it is evident that the population could not be so numerous as it is, were it not sustained by the salt trade of Bilma, which furnishes the people with the means of bartering advantageously with Háusa. As far as I was able to learn from personal information, it would seem that this trade did not take the road by way of Ásben till about a century ago, consequently not before the country was occupied by the Kél-owí. It is natural to suppose that so long as the Tébu, or rather Tedá, retained political strength, they would not allow strangers to reap the whole advantage of such natural wealth.[134] At present the whole authority of Ánnur as well as Lúsu seems to be based upon this trade, of which they are the steady protectors, while many of their nation deem this trade rather a degrading occupation, and incline much more to a roving life. I now return to our encampment near Tintéllust, reserving a brief account of the general features of the country till the moment when we are about to leave it. [Footnote 108: Leo Africanus, Descrizione dell’ Africa, i. c. 6: “E _Air_, diserto ancora esso, ma nomato dalla bontà dell’ aere.” This derivation of the name is manifestly apocryphal. Comp. l. vi. cc. 55. 56.] [Footnote 109: Ebn Batúta’s Travels, ed. Lee, p. 45. Compare Journal Asiatique, 1843, p. 237.] [Footnote 110: Leo, l. vi. c. 55. Ebn Batúta counts seventy days’ march from Tekádda to Tawát, or rather Búda. Now we shall see that Tekádda is situated three days south-west from Ágades, while, from what the traveller says about the place where the road to Egypt separated from that to Tawát, it is evident that he went by Asïu, or rather that the place just mentioned was identical with Asïu. Asïu, then, forty days from Tawát, was thirty days from Tekádda; Káher therefore, being distant eighteen days from Asïu, was twelve days from Tekádda, and was somewhere between the parallels of Selúfiet and Tintéllust, but rather, as we see from the sterile character of the country through which he travelled, and from the situation of Tekádda, in the more barren district to the west. About Tekádda I shall have to speak further on.] [Footnote 111: The Tawárek, as well the Kél-owi as all the other tribes, constantly write [Symbols: ⵔⵢⴰ] (Aïr); and the reason why the Arabs write اهير is simply to avoid the obscenity of أَيْرٌ (_veretrum_).] [Footnote 112: Denham and Clapperton’s Travels, vol. ii. p. 162.] [Footnote 113: I have spoken about the word “tin” before. I have strong reason for supposing that the original name of the place was Ansamán.] [Footnote 114: Ebn Batúta, Journal Asiatique, 1843, série iv. vol. i. p. 188.; Cooley, Negroland, p. 17.]