In the 15th century, Ardabil was the center of an organization designed to keep the Safavi leadership in close touch with its murids in Azerbaijan, Iraq, Eastern Anatolia, and elsewhere. The organization was controlled through the office of "khalīfāt al-khulafā'ī" who appointed representatives ("khalīfa") in regions where Safavi propaganda was active. The "khalīfa", in turn, had subordinates termed "pira". The Safavi presence in eastern Anatolia posed a serious threat to the Ottoman Empire because they encouraged the Shi'i population of Asia Minor to revolt against the sultan.