This article makes a case for the geographical concept of West Asia and develops a specific proposal for its usage: an intervention to open up the closed box of the Middle East to post-Soviet Eurasia in the north and to the rest of Asia in the east. It advances this transregional perspective from the viewpoint of an old imperial frontier, Transcaucasia, and its erstwhile Azeri diaspora. By drawing on archival material, oral histories, contemporaneous print media, and secondary literature, this article traces the movement of Azeris from the Transcaucasian frontier into the political domains of Iranians, Russians/Soviets, and Turks/Ottomans, and show how their movements became avenues for political subversion, territorial expansion, and informal diplomacy over the course of the 20th century and until today.