I would hazard a guess that we have found fossilized human remains of at least a thousand different specimens in South and East Africa, more or less complete at that. I think this is where the prelude to human history was primarily played out.

For fossils to thrive, certain favorable circumstances are required. First of all, of course, remnants of life have to be there. These then need to be washed over with water as soon as possible, so that the bones are covered with a layer of sediment.

I can't think of any other region in the world which is such a vast source of fossils.

Richard Leakey Quotes