Muscovy and the Qing Empire encountered each other in the 1650s in their overlapping frontiers. These encounters took place through imperial intermediaries, agents of empire, who served and embodied the imperial state at its limits. The article examines two intermediaries: Ulanggeri, a Crimean Tatar Cossack who became a Manchu; and Timoshka, a Han Chinese slave who became a Cossack. Comparing these two individuals highlights that both were transfrontier intermediaries recruited into service through passage across the frontier. The diverging fates of these two men reveal important differences between the imperial formations they came to serve.