stylistic:tone
Nomenclature

Marcellinus Comes, a sixth-century Eastern Roman historian and a courtier of Justinian I, mentions the Western Roman Empire in his Chronicle, which primarily covers the Eastern Roman Empire from 379 to 534. In the Chronicle, it is clear that Marcellinus made a clear divide between East and West, with mentions of a geographical east (" Oriens ") and west (" Occidens ") and of an imperial east (" Orientale imperium " and " Orientale respublica ") and an imperial west (" Occidentalie imperium ", " Occidentale regnum ", " Occidentalis respublica ", " Hesperium regnum ", " Hesperium imperium " and " principatum Occidentis "). Furthermore, Marcellinus specifically designates some emperors and consuls as being "Eastern", " Orientalibus principibus " and " Orientalium consulum " respectively. The term Hesperium Imperium, translating to "Western Empire", has sometimes been applied to the Western Roman Empire by modern historians as well.

Though Marcellinus does not refer to the Empire as a whole after 395, only to its separate parts, he clearly identifies the term "Roman" as applying to the Empire as a whole. When using terms such as "us", "our generals", and "our emperor", Marcellinus distinguished both divisions of the Empire from outside foes such as the Sasanian Persians and the Huns. This view is consistent with the view that contemporary Romans of the 4th and 5th centuries continued to consider the Empire as a single unit, although more often than not with two rulers instead of one. The first time the Empire was divided geographically was during the reign of Diocletian, but there was precedent for multiple emperors. Before Diocletian and the Tetrarchy, there had been a number of periods where there were co-emperors, such as with Caracalla and Geta in 210–211, who inherited the imperial throne from their father Septimius Severus, but Caracalla ruled alone after the murder of his brother.