Jura Mountains and Fribourg
The Jura mountains cut through four Swiss cantons: Vaud, Neuchatel, Fribourg, Bern, and Jura. The Swiss Tourist Office lumps the Jura Vaudois in with the Lake Geneva Region which does make sense as odds are if you visit there you'll be sleeping in a lakeside city like Nyon. The northern Jura are more heavily populated, and are represent a distinct culture from the rest of French speaking Switzerland.
The cities of the Northern Jura are where the famed Swiss watch making industry took off in the 18th and 19th centuries, and so there are a lot of interesting watch-making related things to see in the region.