In the 1930s and early 1940s, China was at war with Japan and China’s Nationalist government moved to Sichuan Province in the Southwest. An ideal location in many ways, Southwest China was also an ethnically diverse place, a crucible for the idea of a modern, unified Chinese nation held together by its constituents. The region became a seedbed for frontier studies and the rethinking of ethnic relations, a region that academics and administrators hoped to transform into a bastion of military resistance and national recovery. This article argues that Pan-Thai nationalism, promoted by the Thai state to spread Thai consciousness among Tai minorities in Southwest China, provided an impetus for these trends. Unity became the national purpose, and the cultural and economic development of Southwest China was conceptualized.