Complex sentence: Reigning for only ten months, his legitimacy and authority disputed beyond Italy, Romulus was then deposed by Odoacer, who had defeated and executed Orestes, and sent Romulus to live in the Castellum Lucullanum in Campania; afterwards he disappears from the historical record.
Split into simpler sentences: Reigning for only ten months, his legitimacy and authority disputed beyond Italy, Romulus was deposed by Odoacer, who had defeated and executed Orestes. Odoacer sent Romulus to live in the Castellum Lucullanum in Campania, after which he he disappears from the historical record.