Ottomans wrote the whole playbook for Middle Eastern dictators: systematically favor the ethnoreligious groups you like, ensure that any big business opportunities are channeled through them, and then for disfavored ethnoreligious groups, suppress avenues to wealth which can be used against their rulers. Then, with the massive vacuum of intelligence left behind as a result of this policy, let fundamentalists misuse religion in such a way to keep your opponents simple and stupid (whereas during the Islamic Golden Age, scientists were inspired by Islam to make groundbreaking discoveries, and they in turn helped spark the Enlightenment in Europe).
Baghdad is smaller today than it was then. Just to show how much of an impact was felt.