The twelve dioceses of the Empire, as constituted under Diocletian, were (1) Oxiens; (2) Pontica; (3) Asiana; (4) Thracia; (5) Mœsia; (6) Pannonia; (7) Britanniæ; (8) Galliæ; (9) Viennensis; (10) Italiciana; (11) Hispaniæ; (12) Africa.