Nationalist tensions in the Balkans primarily stemmed from the 19th-century decline of the Ottoman Empire. As the multi-ethnic empire weakened, its subject peoples, inspired by Romantic nationalism, sought independence and distinct nation-states. The Balkans were highly diverse, home to Slavs, Greeks, Albanians, and Romanians. Each group asserted unique identities based on language and culture, leading to fierce rivalries and conflicting territorial claims, as nascent nations tried to expand at neighbours' expense. This was exacerbated by European Great Powers (Russia, Austria-Hungary, etc.) intervening with their strategic interests. They supported different Balkan factions, intensifying local conflicts. This volatile mix of imperial collapse, surging ethnic nationalism, and external meddling turned the Balkans into a 'powder keg,' contributing to significant European conflicts.