Why was the Balkan Peninsula known as the powder keg of Europe?

The Balkan Peninsula was known as the "powder keg of Europe" due to its complex mix of ethnic groups, nationalistic tensions, and historical grievances, which created a highly volatile political environment. The decline of the Ottoman Empire in the late 19th and early 20th centuries further exacerbated these tensions as various nations sought independence or territorial expansion. This instability was a significant factor leading to the outbreak of World War I, as local conflicts had the potential to ignite broader European hostilities. The region's strategic importance and the involvement of major powers made it a focal point for conflict.