From what I have been told, some of these beads may indeed be in the range of a thousand or thousands of years old, but.........it is also quite possible a fair number of them are no more than a few hundred years old. The techniques of pecking, grinding on a stone etc could easily have been used much more recent than we would think, simply because more modern techniques were not yet available in parts of Africa.

I'm hoping Thomas will add to this discussion too....