Ancient Numibia was situated in what is now known as Algeria with a bit of Tunisia and Libya so you can vary the skin tones from dark brown to Mediterranean.
The Foundry North African triad is a good colour, for darker skins there is the Reaper Dark Skin triad 9040/1/2 and for really dark skin there is the GW Rhinox Hide combo Capt. Blood used or a combination of Burnt Umber/Burnt Sienna/Raw Umber.