Geographically, the empire was divided into several provinces, the borders of which changed numerous times during the Umayyad reign.
To assist the Caliph in administration there were six Boards at the Centre: Diwan al-Kharaj (the Board of Revenue), Diwan al-Rasa'il (the Board of Correspondence), Diwan al-Khatam (the Board of Signet), Diwan al-Barid (the Board of Posts), Diwan al-Qudat (the Board of Justice) and Diwan al-Jund (the Military Board) .