What region in southeastern Europe is known for its mountainous terrain and was a focal point of conflict in the early 20th century?

The Balkans is the region in southeastern Europe characterized by its rugged mountainous terrain and history of conflict, particularly during the early 20th century. This area has been shaped by a complex array of ethnic groups, national identities, and historical grievances, leading to significant tension and conflict, especially during the Balkan Wars (1912-1913) and World War I. The geographical features of the Balkans, including its mountains, have historically made it both a barrier and a point of contention among various groups, contributing to the region's tumultuous political landscape.

In contrast, the Pyrenees are a mountain range that forms the border between Spain and France, and they do not relate directly to the southeastern European context. Scandinavia refers to a region in northern Europe known for its relatively flat terrain and different historical paths, while the Caucasus region, although mountainous and also significant in various conflicts, is located between Eastern Europe and Western Asia and has its own distinct ethnic and political challenges separate from those of the Balkans.