Columbia subject headings:
Hejaz (Saudi Arabia)--History.
Islamic Empire--History--622-661.
Islamic Empire--History--661-750.
Harvard subject headings:
Hejaz (Saudi Arabia)--History.
Islamic Empire--History--622-661.
Islamic Empire--History--661-750.
Princeton subject headings:
Hejaz (Saudi Arabia)--History.
Islamic Empire--History--622-661.
Islamic Empire--History--661-750.