<P> In historiography , the Western Roman Empire consists of the western provinces of the Roman Empire at any one time during which they were administered by a separate independent Imperial court , coequal with ( or only nominally subordinate to ) that administering the eastern half . Both `` Western Roman Empire '' and `` Eastern Roman Empire '' ( or `` Byzantine Empire '' ) are modern terms describing de facto independent entities ; however , at no point did the Romans consider the Empire split into two , but rather considered it a single state governed by two separate Imperial courts out of administrative expediency . The view that the Empire was impossible to govern by one emperor was established by Diocletian following the disastrous civil wars and disintegration of the Crisis of the 3rd century , and was instituted in Roman law by his introduction of the Tetrarchy in AD 285 , a form of government which was legally to endure in one form or another for centuries . The Western Court was periodically abolished and recreated for the next two centuries until final abolition by Zeno in 480 , by which time there was little effective central control left in the area legally administered by the Western Court . </P>
<P> In historiography , the Western Roman Empire consists of the western provinces of the Roman Empire at any one time during which they were administered by a separate independent Imperial court , coequal with ( or only nominally subordinate to ) that administering the eastern half . Both `` Western Roman Empire '' and `` Eastern Roman Empire '' ( or `` Byzantine Empire '' ) are modern terms describing de facto independent entities ; however , at no point did the Romans consider the Empire split into two , but rather considered it a single state governed by two separate Imperial courts out of administrative expediency . The view that the Empire was impossible to govern by one emperor was established by Diocletian following the disastrous civil wars and disintegration of the Crisis of the 3rd century , and was instituted in Roman law by his introduction of the Tetrarchy in AD 285 , a form of government which was legally to endure in one form or another for centuries . The Western Court was periodically abolished and recreated for the next two centuries until final abolition by Zeno in 480 , by which time there was little effective central control left in the area legally administered by the Western Court . </P>
when was rome divided into east and west
when was rome divided into east and west
AD 285
AD 285