If you needed a pictorial view of BPM history in one screenshot, Marco Brambilla has it for you.? Of course, this is just from one perspective and anything this simple can be nitpicked, but it does capture some interesting trends over the years, precursors to BPM, etc.:
Side Note: I should also thank Marco for including the BP3 blog in his list of prominent BPM blogs to read.? Many thanks for the compliment, Marco.