when was the roman empire divided into east and west
Western Roman Empire
Though the Empire had seen periods with more than one Emperor ruling jointly before , the view that it was impossible for a single emperor to govern the entire Empire was established by Emperor Diocletian following the disastrous civil wars and disintegrations of the Crisis of the 3rd century . His ideas were instituted in Roman law by the introduction of the Tetrarchy in AD 286 , which divided the position of Augustus ( Emperor ) into two ; one in the East and one in the West , each with an appointed Caesar ( junior Emperor and designated successor ) . Though the tetrarchic system would collapse in a matter of years , the East - West geographical administrative division would endure in one form or another for centuries to come . As such , the Western Roman Empire would exist intermittently in several periods between the 3rd and 5th centuries . Though some emperors , such as Constantine I and Theodosius I , would manage to rise to the position of Augustus in both halves and as such reunify the Empire , it would often divide again upon their deaths . After the death of Theodosius I in AD 395 , the Empire was divided between his sons after which it would never again be unified . Eighty - five years later , in 480 , following various invasions and the collapse of central control in the West , Zeno of the Eastern Empire recognized the reality of the Western Empire 's reduced domain -- effective central control had ceased to exist even in the Italian Peninsula after the depositions of Julius Nepos and Romulus Augustulus -- and therefore abolished the Western court and proclaimed himself the sole emperor of the Roman Empire . 
Though the Empire had seen periods with more than one Emperor ruling jointly before , the view that it was impossible for a single emperor to govern the entire Empire was established by Emperor Diocletian following the disastrous civil wars and disintegrations of the Crisis of the 3rd century . His ideas were instituted in Roman law by the introduction of the Tetrarchy in AD 286 , which divided the position of Augustus ( Emperor ) into two ; one in the East and one in the West , each with an appointed Caesar ( junior Emperor and designated successor ) . Though the tetrarchic system would collapse in a matter of years , the East - West geographical administrative division would endure in one form or another for centuries to come . As such , the Western Roman Empire would exist intermittently in several periods between the 3rd and 5th centuries . Though some emperors , such as Constantine I and Theodosius I , would manage to rise to the position of Augustus in both halves and as such reunify the Empire , it would often divide again upon their deaths . After the death of Theodosius I in AD 395 , the Empire was divided between his sons after which it would never again be unified . Eighty - five years later , in 480 , following various invasions and the collapse of central control in the West , Zeno of the Eastern Empire recognized the reality of the Western Empire 's reduced domain -- effective central control had ceased to exist even in the Italian Peninsula after the depositions of Julius Nepos and Romulus Augustulus -- and therefore abolished the Western court and proclaimed himself the sole emperor of the Roman Empire .
The view that it was impossible for a single emperor to govern the entire Empire was established by Emperor Diocletian following the disastrous civil wars and disintegrations of the Crisis of the 3rd century. His ideas were instituted in Roman law by the introduction of the Tetrarchy in AD 286 , which divided the position of Augustus ( Emperor ) into two ; one in the East and one in the West. Constantine I and Theodosius I , would manage to rise to the position of Augustus in both halves and as such reunify the Empire, but it would divide again upon their deaths. After the death of Theodosius I in AD 395 , the Empire was divided between his sons after which it would never again be unified .
Though the Empire had seen periods with more than one Emperor ruling jointly before , the view that it was impossible for a single emperor to govern the entire Empire was established by Emperor Diocletian following the disastrous civil wars and disintegrations of the Crisis of the 3rd century . His ideas were instituted in Roman law by the introduction of the Tetrarchy in AD 286 , which divided the position of Augustus ( Emperor ) into two ; one in the East and one in the West , each with an appointed Caesar ( junior Emperor and designated successor ) . Though some emperors , such as Constantine I and Theodosius I , would manage to rise to the position of Augustus in both halves and as such reunify the Empire , it would often divide again upon their deaths . After the death of Theodosius I in AD 395 , the Empire was divided between his sons after which it would never again be unified .
The view that it was impossible for a single emperor to govern the entire Empire was established by Emperor Diocletian following the disastrous civil wars and disintegrations of the Crisis of the 3rd century. His ideas were instituted in Roman law by the introduction of the Tetrarchy in AD 286 , which divided the position of Augustus ( Emperor ) into two ; one in the East and one in the West. Constantine I and Theodosius I would manage to rise to the position of Augustus in both halves and as such reunify the Empire, but it would divide again upon their deaths. After the death of Theodosius I in AD 395 , the Empire was divided between his sons after which it would never again be unified .
Though the Empire had seen periods with more than one Emperor ruling jointly before , the view that it was impossible for a single emperor to govern the entire Empire was established by Emperor Diocletian following the disastrous civil wars and disintegrations of the Crisis of the 3rd century . His ideas were instituted in Roman law by the introduction of the Tetrarchy in AD 286 , which divided the position of Augustus ( Emperor ) into two ; one in the East and one in the West , each with an appointed Caesar ( junior Emperor and designated successor ) . Though some emperors , such as Constantine I and Theodosius I , would manage to rise to the position of Augustus in both halves and as such reunify the Empire , it would often divide again upon their deaths . After the death of Theodosius I in AD 395 , the Empire was divided between his sons after which it would never again be unified .