In recent years, scholars of international legal history have demonstrated much newfound interest in C.H. Alexandrowicz, a Polish jurist renowned for his anti-Eurocentric revisionist account of Asian and African agency within the meta-narrative of international law. Building on efforts to link his Polish origins with his studies of the Afro-Asian world, especially on matters of imperialism and state personality, my purpose in this Article is to explore these connections through a materially grounded historical sociology of international legal thought. Centering the issue of whether sovereignty is divisible, I situate the historic Polish-Lithuanian Commonwealth—extinguished by a series of Partitions in 1772, 1793, and 1795—as a unique divided sovereignty-based polity that provided a basis for Alexandrowicz’s study of the juridical status of non-European sovereigns. This analogy united his overarching critique of nineteenth-century international legal positivism as an unjustifiable denial of both Polish and Afro-Asian sovereignty. In deciphering the materiality of Alexandrowicz’s imagination against this presumption, I build a narrative of the Polish-Lithuanian Commonwealth and the evolution of its distinct approach to sovereign divisibility. Through analysis of the interplay between internal and external factors, I account for the Commonwealth’s medieval origins, its development in opposition to the consolidating indivisible sovereignty of its absolutist neighbors, its attempts to maintain independence in the face of Partition, and the continued assertions of its variegated legacies following its destruction. This, I argue, provides a novel means of assessing Alexandrowicz’s theory, and the materiality of international law more generally.