East Asia is rarely identified as a distinctly Muslim space. This article sheds light on the hitherto neglected history of modern East Asia as a site of Muslim activity and encounters. Mobile Muslims, who travelled and migrated to the East Asian space in the course of imperial globalization, often suffered discrimination as colonized subjects, but in other instances benefitted from imperial privileges and protection. The Tatars of Harbin, who came to Manchuria as Russian subjects, are emblematic, but understudied, actors in this regard. The city of Harbin, administered by the Russian-controlled Chinese Eastern Railway, emerged in the late nineteenth century as a rapidly growing transport hub and colonial settlement in Manchuria. Similar to colonial port cities, Harbin simultaneously exhibited characteristics of both the metropolis and the multi-ethnic and multi-religious composition of the empire. This situation created many opportunities for Tatars to seek their fortunes, especially in trade. Zooming in on the Harbin Tatars, this article discusses, first, the place of Tatar Muslims and their institutions in Harbin’s colonial society; second, the intertwining of notions of (economic) competition in the colonial space with ideas of progress and decline; and third, the potential for Muslim encounters across colonial boundaries. Taking into account the Muslim side of modern East Asian history is not only an essential part of understanding the development of global connections, it also helps us to rethink the dichotomy between colonizer and colonized, and focus our attention on the ambitions of Muslim actors in shaping their futures across the colonial space.