Columbia subject headings:
Egypt--History--640-1250.
Islamic Empire--History--750-1258.
Harvard subject headings:
Assassins--Middle East--History.
Caliphs--History.
Crusades--First, 1096-1099
Egypt--History--640-1250.
Islamic Empire--History--750-1258.
Princeton subject headings:
Egypt--History--640-1250.
Islamic Empire--History--750-1258.