Through the thick affective analysis of a carved ivory horn now in the Metropolitan Museum of Art, this study traces the millennium-long development of several insidious geographies, a term I use to describe diverse assemblages of material, visual, textual, and intellectual culture entangled with a variety of cultural, political, and economic regimes that perpetuate themselves through naturalizing and aestheticizing the violence they deploy towards pernicious ends. Using a combination of object biography and life history methodologies, I situate the carved horn, a so-called oliphant, within its early life history in the medieval Mediterranean (ca. 750–1792 CE) and its later, documented object biography including its accession into the Met and its role in the development of the discipline of Islamic art history (1792–present). Using the horn itself as well as diverse examples of material, visual, and textual culture of the relevant periods, I demonstrate the horn’s complicity in the creation of medieval and modern pernicious geographies of East and West, simultaneously exposing the insidious mechanisms of action of such geographies. In light of this, the paper calls for a critical reassessment of the term “oliphant” and renewed attention from scholars to the entanglement of the materials of their study, particularly ivory, with such insidious geographies.