The term exarch entered ecclesiastical language at first for a metropolitan (an archbishop) with jurisdiction not only for the area that was his as a metropolitan, but also over other metropolitans within local political dioceses. Since imperial vicarius (governor of a political diocese) was often called "exarch" in eastern, Greek speaking parts of the Empire, it became customary for the metropolitans of the diocesan capitals (Ephesus in the Diocese of Asia, Heraclea in the Diocese of Thrace and Caesarea in the Diocese of Pontus) also to use the title "exarch" in order to emphasize their precedence and primatial status over other metropolitans within local political dioceses.