They would have likely used a collection of East-is-Up maps to get from destination to destination. The medieval maps were maps, however they were designed to allow you to navigate from natural markings as there was no such thing as a compass, you only had the sun to tell you was going in the right direction. Similarly many of these maps were point A to point B maps, with the destination at the top, you found the path it was describing and simply followed the route.

Notable objects were used to navigate, for instance the Tree of Ténéré is still frequently drawn on maps as it was the only tree for 200km (now it's simply a statue to where the tree once was). It was a key marker for trade caravans.

They would also have likely used a great many of local navigators, as explorers still do today. Our great explorers were merely bumbling idiots who got incredibly lucky in finding amazing local explorers who had lived the land for decades.