Sahara Unveiled, by William Langewiesche, is a fine book. He traveled around and across the Sahara by local transit and writes about it beautifully. He likes the people and respects but does not romanticize them. This is a harsh unbeautiful landscape and the writing is often that way. There are surprising illustrations of petroglyphs.
There are several descriptions of death by thirst when lost in the desert (people who die that way often leave memoirs, because it takes a while) that are frankly harrowing and you might want to skip over. The author was himself abandoned in one of the most remote corners of the Sahara and faced such a death himself, which makes for a gripping narrative.
I thought the following remark worth quoting in full:
The concept of pure ethnicity is as dangerous as that of pure race. All people are mongrels. “Indigenous” societies are subject to the same requirements for change as others. There is no such construct as an inauthentic culture.