In The Origins of the Ottoman Empire, Köprülü criticized as unscientific the prevailing Western explanations of the origins of the Ottoman Empire. Leiser's translation from the Turkish reveals Köprülü's modern historiographic method, and his unique contribution in describing the nature of the relevant Muslim sources. Using these and other references, Köprülü gave the first broad comprehensive account--political, religious, social, and economic--of the Turkish history of Anatolia in the thirteenth and fourteenth centuries, and outlined the major factors that led to the rise of the Ottomans.