This article tells the archival story of how Rawls invented a hypothetical Muslim state that he called “Kazanistan.” It examines drafts of The Law of Peoples from 1992 to 1998, Rawls's notes, his personal correspondence, and the sources preserved in his archives. I track Rawls's gradual interest in Islam, which resulted in his invention of Kazanistan during the final revisions, in March 1998. Contrary to the aesthetics of rigor and simplicity in ideal theory's methods, Rawls's actual method in his incursion into “comparative philosophy” and Islam was circuitous and contingent. And contrary to ideal theory's self-presentation as emerging from an ahistorical conceptual realm, the idealized abstraction of Islam emerges from Rawls's own history, or from an ideologically limited set of texts, conversations, and political debates about Islam. The genealogy of Kazanistan illustrates how liberal philosophy extracts data from other disciplines to construct other peoples, without regard for the surrounding disciplinary politics.