The main type of habitation in the oases and valleys consists of fortified structures, the architectural style of which is derived from many very different influences, especially eastern and pre-Islamic Mediterranean. Most of the casbahs are built on precipitous heights creating an imperious sense of isolation. They are all built in the same style and design and only the various ornamental brickwork patterns differ from one to the other. This decoration is not sophisticated but is dictated simply by the size of the building. In fact, once the construction reaches a certain height, it is difficult to use the normal pisé due to the weight of the wet earth which constitutes the basis of this building material. The walls are therefore finished with pre-dried bricks that are easier to transport. But even here it can be seen that the proud solitude of these places, so strongly rooted in their traditions. has felt the impact of modernity. Indeed, here and there, small bars, telephones and occasional power lines have appeared.