Upper Senegal and Niger, Vol. 2

The ruins teach us even less: except, I believe, among the Tombo of the cliffs, one only builds in the Sudan with clay and wood. Only the foundations of the walls are often made of raw stones, laid with mud. Thus the ruins that one may encounter are inevitably recent: I estimate that after two centuries at the most, no trace remains of these constructions, which are so fragile and so quickly reclaimed by the earth.

I say "in general," because I would not want to be too assertive. Thus, it is a constant fact that polished stone axes are considered almost everywhere, by the current natives of the Sudan, as stones that have fallen from the sky; it is claimed that, when lightning strikes, it is one of these stones that causes the damage. This interpretation would tend to prove the antiquity of the stone axes that one finds in the Sudan, since the current natives attribute their origin to a natural phenomenon.