Some mountains ranges (such as the Ahaggar, Tassili n'Ajjer, Tibesti and Aïr) rise up from the desert and receive more rainfall and mostly present slightly cooler summer temperatures.

The boundaries for the largest part of this ecoregion, which includes the Tassili n'Ajjer Ahaggar and Aïr (or Azbine) massifs, follow the 'regs,' 'hamadas' and 'wadis' above the 1,000 m contour.

[2] The mountains of the West Saharan montane xeric woodland ecoregion are found within the Sahara Desert and are predominantly of volcanic origin.

They rise from the surrounding flat desert landscape or sand dunes and create islands of moister habitat (guelta) which support flora and fauna.

The most important area is the Tassili n'Ajjer Plateau, an outlier of the Ahaggar Mountains in Algeria which supports some near-endemic species and some globally threatened antelopes.

Olive and myrtle trees grow at the bottom of wadis, intermittent stream valleys, or beside gueltas and permanent or temporary waterholes.