Postage stamps issued by Nagorno-Karabakh or Republic of Artsakh aren't recognized on an international level, either by UPU nor by PostEurop. Those stamps are listed in most stamps catalogues. Nagorno-Karabakh (self-declared Republic of Artsakh) is a disputed territory between  Armenia and Azerbaijan. Nagorno-Karabakh is a landlocked region in the South Caucasus and is recognized by the United Nations as part of Azerbaijan.