This chapter examines Nagorno-Karabakh conflict as an example of unresolved ethno-territorial disputes in the post-Soviet space. Emerging in the late Soviet era, it has escalated through wars in the 1990s, 2020, and 2023, causing mass displacement and contested claims of sovereignty and self-determination. Russia’s ambiguous role has deepened instability while advancing its geopolitical interests. Turkey and Iran have pursued more indirect involvement, shaped by cultural and strategic ties. Legal disputes, humanitarian crises, and competing nationalist narratives highlight both the human costs and the enduring complexity of conflict resolution in the South Caucasus.