Complex sentence: It was formed in 1792, when the Savoy region, (part of the Kingdom of Sardinia) was occupied by the French, and ceased to exist following Napoleon's defeat at Waterloo and the territory was restored to its former rulers.
Split into simpler sentences: It was formed in 1792, when the Savoy region, (part of the Kingdom of Sardinia) was occupied by the French. The department ceased to exist following Napoleon's defeat at Waterloo when the territory was restored to its former rulers.