South of Marrakech the road winds over a pass in the High Atlas, leaving the fertile costal plain and coming down into the arid fringes of the Sahara desert. Here the Dades and Draw valleys carry the High Atlas snowmelt on its route to be consumed by the sands. Littering these valleys are the remains of clan fortresses marking the edge of habitable north africa, no doubt the end points for what trade remained from Timbuctu and elsewhere. These rammed earth kasbahs are the most indigenous of Moroccan buildings, unique and closer to african architecture in the south than the Moorish architecture in the north.