The western part after the Roman Empire was divided in 395; it lasted only until 476 WordNet 3.0 & Open English WordNet

The term Western Roman Empire is used in modern historiography to refer to the western provinces of the Roman Empire, collectively, during any period in which they were administered separately from the eastern provinces by a separate, independent Imperial court. Wikipedia

The western half of the Roman Empire Wikipedia Disambiguation

Independently administered western provinces of the Roman Empire Wikidata

The western half of the Roman Empire, from its division by Diocletian in 286. Its capital was in Mediolanum OmegaWiki