The region sometimes known as Manchuria entered 1900 as a frontier of blurred boundaries. Inter-polity borders between the Qing and Russian empires, and between both empires and Korea, had been drawn in earlier centuries, but no power center exerted full control. Multiple populations—Manchu, Korean, Han Chinese, Russian, and also Japanese for a time—lived among one another. This changed by mid-century as borders hardened under new rationalist-Westphalian states, the PRC, USSR, and DPRK. Yet, as this article argues in a revisionist, multi-perspectival account, the Manchurian frontier had a long afterlife in the politics and culture of the PRC and its avowedly modern socialist neighbors. Historical and anthropological insights at the local level reveal how ubiquitous Manchurian frontier “bandits” were supplanted by Chinese, Russian, and Korean “partisans” during the 1920s–1940s revolutionary conflicts. As guerrilla fighters drew on romanticizations of noble, masculine bandit-heroes, the socialist causes—and ultimately states—they fought for became embedded in both the Manchurian wilderness and local imagination.