This article examines the impact of the Ottoman Empire's battle against legal imperialism on the status of Central Asians in its domains, specifically after the promulgation of a nationality law in 1869 that classified them as foreigners. It traces how the threat of Muslim colonial subjects attaining European consular protections led to the emergence of a “Central Asian protection question”: whether Afghans, Bukharans, and Chinese Muslims had legitimate claims to European legal nationality and, by extension, capitulatory privileges. Through a number of case studies, the article shows how the Ottoman Foreign Ministry fused international legal norms and pan-Islamic claims to arrive at the position that Central Asians from informally colonized lands were not “real” subjects of European empires, and that they were under the exclusive protection of the caliphate. This strategy, I argue, undermined the creation of an Ottoman citizenship boundary and opened up a complex field of inter- and intraimperial contestation about who was a foreigner. In contrast to positive associations with legal pluralism in this period, Central Asian migrants and pilgrims who were protected by the caliph but not recognized as Ottomans or European subjects found that they could not benefit from practices such as forum shopping and affiliation switching. And while the notion of foreignness remained subject to multiple and conflicting interpretations across the empire, I argue that nationality as a legal category was incontrovertibly becoming a defining feature of these foreign Muslims' rights and status in the sultan's domains.