Why were the balkans and called the “power keg” of europe

The Balkans were called the "Powder Keg" of Europe, not the "Power Keg" of Europe.

Explanation:

The Balkans are a highly multicultural region with a long history of conquest. The major empires of European History have occupied the zone and left a mark there.

The Balkans present a diversity of religions: Islam, Catholicism, Orthodox Christians, and others. Ethnic and Linguistic cleavages are also evident.

Historically speaking, the main problem with the Balkans is that the continued occupation by foreign powers and empires has fostered artificial political borders that fuel ethnic resentment. Geographically the Balkans are a crucial area between Europe and Asia and have been the object of continued international tension. In the 19th century, Russia tried to align itself with the Slavic ethnic groups of the region and helped them in independence attempts against the Ottoman Empire and the Austro Hungarian Empire. All the accumulated tension, resentment and budding nationalism create a region that is like a keg of powder, ready to explode with any minimal spark.

the northwest ordinance of 1787 guaranteed basic rights for settlers and banned slavery there.