Columbia subject headings:
Harvard subject headings:
Islamic Empire--History--622-661.
Islamic Empire--History--661-750.
Islamic Empire--History--750-1258.
Islamic Empire--Military policy.
Islamic Empire--Politics and government.
Princeton subject headings:
Iraq--History, Military.
Iraq--Politics and government.
Islamic Empire--History--750-1258.
Syria--History, Military.
Syria--Politics and government.