History of the Roman Empire
Theodosius was the last Emperor who ruled over the whole Empire. After his death in 395, he gave the two halves of the Empire to his two sons Arcadius and Honorius; Arcadius became ruler in the East, with his capital in Constantinople, and Honorius became ruler in the West, with his capital in Milan and later Ravenna. The Roman state would continue to have two different emperors with different seats of power throughout the 5th century, though the Eastern Romans considered themselves to be the only ones who were fully Roman. Latin was used in official writings as much as, if not more than, Greek and the two halves were nominally, culturally and historically, if not politically, the same state.
Fall of the Western Roman Empire
By convention, the Western Roman Empire is deemed to have ended on 4 September 476, when Odoacer deposed Romulus Augustulus and proclaimed himself ruler of Italy, but this convention is subject to many qualifications. In Roman constitutional theory, the Empire was still simply united under one emperor, implying no abandonment of territorial claims. In areas where the convulsions of the dying Empire had made organized self-defence legitimate, rump states continued under some form of Roman rule after 476. Julius Nepos still claimed to be Emperor of the West and controlled Dalmatia until his murder in 480. Syagrius son of Aegidius ruled the Domain of Soissons until his murder in 487. The indigenous inhabitants of Mauretania developed kingdoms of their own, independent of the Vandals, with strong Roman traits. They again sought Imperial recognition with the reconquests of Justinian I, and they put up effective resistance to the Muslim conquest of the Maghreb. While the civitates of Britannia sank into a level of material development inferior even to their pre-Roman Iron Age ancestors, they maintained identifiably Roman traits for some time, and they continued to look to their own defence as Honorius had authorized.