What region was known as powder keg of Europe?

The Balkans were often referred to as the "powder keg of Europe" due to the intense ethnic tensions, nationalism, and political instability that characterized the region, particularly in the early 20th century. This volatility contributed to the outbreak of World War I, as various nationalist movements and conflicts among the diverse ethnic groups created a highly combustible environment. The assassination of Archduke Franz Ferdinand in Sarajevo in 1914 is often cited as the spark that ignited this "powder keg."