Why do different sources include different countries in the Balkans?

There is no universal agreement on the composition of the Balkans because the region is defined through varying, often overlapping, geographic, cultural, and historical lenses rather than a single, fixed standard.12

The inclusion of specific countries often depends on the criteria used:

• Geographic Definitions: The Balkans are primarily defined as a peninsula, but because the region lacks a clear northern geographic boundary, definitions vary. While most core states are consistently included, countries like Moldova are sometimes added due to historical and cultural ties to Romania, despite being located north of the Danube River.1
• Historical and Political Context: Countries like Slovenia are frequently included due to their former membership in Yugoslavia and historical ties to the region. Conversely, Greece and Turkey are often included because parts of their territory lie on the peninsula, though they are frequently categorized by their Mediterranean or Anatolian identities.1
• Terminology: The emergence of terms like "Western Balkans" and "South East Europe" has further diversified how observers group these states, reflecting shifting political and economic priorities.1