Actually there are/were a lot of very bad Arabs (and other non-indigenous people) in Afghanistan, at least as the backbone of AQ and some of the other forces. A small number vs. the overall population, but a high percentage of the hardcore bad guys. Less true of Taliban or local gangs (who are who we fight now, for no particularly good reason -- the Taliban is "bad" from a liberal Western perspective, but not bad enough, IMO, to justify invading/occupying. We're in Afghanistan now because we were in Afghanistan yesterday; it's the sunk costs fallacy in blood.).