The powder keg of Europe or Balkan powder keg was the Balkans in the early part of the 20th century preceding World War I. There were many overlapping claims to territories and spheres of influence between the major European powers such as the Russian Empire, the Austro-Hungarian Empire, the German Empire and, to a lesser degree, the Ottoman Empire, the United Kingdom and the Kingdom of Italy.
In addition to the imperialistic ambitions and interests in this region, there was a growth in nationalism with the indigenous peoples of this region leading to the formation of the independent states of Greece, Serbia, Montenegro, Bulgaria, Romania and Albania.
These tensions had boiled over during the decades long diplomatic crisis in the Balkans: starting with the Macedonian Struggle, the Balkan Wars, and then the 1914 Greco-Turkish war scare, though the Great Powers ruled out military intervention with the region until the assassination of Franz Ferdinand.