I realize that is a farfetched, even shocking notion to FR readers, but it's just possible that the genocidal rapists and slavers of the religion of pieces may have had something to do with the decline of the place. OTOH, there's not much evidence of that kind of thing, other than the underground cities in Turkey that can house 20,000 people, stuff like that. :^) :^D
You got it.....the Muzzies horrid reputations proceeded them and people prepared for it.