when did the roman empire split into two parts
Western Roman Empire In historiography, the Western Roman Empire refers to the western provinces of the Roman Empire at any time during which they were administered by a separate independent Imperial court, coequal with that administering the eastern provinces, referred to as the Eastern Roman Empire. The terms "Western Roman Empire" and "Eastern Roman Empire" are modern inventions that describe political entities that were de facto independent. At no point did the Romans themselves consider the Empire to have been split into two separate Empires. They considered it remained a single state that was governed by two separate Imperial courts as an administrative expediency. A system of government of this kind is known as a diarchy.