Where Did a hotbed of nationalist and ethnic rivalries exist in ther early 1900s?

In the early 1900s, a hotbed of nationalist and ethnic rivalries existed in the Balkans, a region in Southeast Europe. This area was characterized by a complex web of ethnic groups, including Serbs, Croats, Bulgarians, and Albanians, each striving for national sovereignty and territorial claims. The decline of the Ottoman Empire further exacerbated these tensions, leading to conflicts such as the Balkan Wars. These rivalries ultimately contributed to the outbreak of World War I.