Complex sentence: In 403 the king of the Visigoths, Alaric I, invaded northern Italy from Dalmatia: setting himself in Verona, he was however defeated by the Roman general Stilicho.
Split into simpler sentences: In 403 the king of the Visigoths, Alaric I, invaded northern Italy from Dalmatia. After setting himself up in Verona, he was defeated by the Roman general Stilicho.