Even though in the 4th century divided governing of the country became more evident and the West of Rome was called as "the emperor of the West" or "the territory of the West", it was not officially called the Western Roman Empire and "the Roman Empire" was considered to govern the both territories.
4世紀に分治の色が濃くなったものの、当時「西の皇帝」「西の領土」などとは言われても「西ローマ帝国」とは言われず、あくまで「ローマ帝国」の分割統治であった。