Sahara Desert (or Desert of Sahara) was a desert region of northern Africa.
In The Big Good-Bye, Paddy Fallon, a friend of Detective Jim Tierney, asked him if he considered moving to a more lively place than the Northern Valley where his saved money could work for him. Perhaps, according to Fallon, Tierney could set up shop selling fishing tackle in the Sahara Desert. (TNG: "The Big Goodbye")
The pages seen in the episode were actually from the detective novel, The Listening Man, by author John A. Moroso. This novel was published in 1924. Information on Sahara Desert was from page 109.
The Sahara also indirectly lent its name to the Sub-Sahara, referenced in the title of the book Languages of the Sub-Sahara.