Roman imperial dynasties Valentinian dynasty Chronology Valentinian I as Emperor of the West 364–375 -with Valens as Emperor of the East 364–375 -with Gratian as junior Augustus of West 375–378 Gratian as Emperor of the West 375–383 -with Valentinian II as junior Augustus of West 375–378 -with Valens as Emperor of the East 375–378 Gratian as sole emperor 378–379 -with Valentinian II as junior Augustus 375–379 Gratian as Emperor of the West 379–383 -with Theodosius I as emperor of the East 379–383 -with Valentinian II as junior Augustus 375–383 Interlude: Magnus Maximus Usurper 383–388 Valentinian II in competition with Magnus Maximus in the west 383–388 -with Theodosius I as emperor of the East 375–388 Valentinian II as Emperor of the West 388–392 -with Theodosius I as emperor of the East 388–392 Western Empire Interlude: Honorius Theodosian dynasty 393–423 Interlude: Joannes Usurper 423–425 Valentinian III as Emperor of the West 425–455 Succession Preceded by Constantinian dynasty and Jovian Followed by Non dynastic emperors (455–480) in the west and Theodosian dynasty in the east