Complex sentence: A. Watson (1999), p.34 After devastating Germania Superior and Raetia (parts of southern France and Switzerland), they entered Italy, the first invasion of the Italian peninsula, aside from its most remote northern regions, since Hannibal 500 years before.
Split into simpler sentences: A. Watson (1999), p.34 After devastating Germania Superior and Raetia (parts of southern France and Switzerland), and entered Italy. It was the first invasion of the Italian peninsula, apart from its remotest northern regions, since the days of Hannibal, 500 years before.