By unearthing the environmental history of development and disease in the peripheral triangle of territory between Aleppo, Mosul, and Baghdad between 1858 and 1939, my project explores the connections between infrastructure and illness, between humans and non-human nature, and between the Ottoman and post-Ottoman world. The work follows bureaucrats and beasts of burden, railroads and rinderpest, and peasants and Pasteur-Institute-trained scientists to tell a synthetic story of the integration and disintegration of this space under Ottoman imperial, Turkish and Iraqi republican, and British and French colonial authorities, illuminating continuities obscured in the limited temporal scope and spatial scale of historical accounts bounded by particular political regimes or state-defined spaces. Beginning with Ottoman modernization efforts in the mid-nineteenth century, the project explores how roads and rails created a unified space between and around these three cities, and how epidemics illuminated this degree of cohesiveness. Additionally, I follow how health interventions underpinned by new understandings of disease based on germs enabled innovative interventions into the lives of humans, plants, and animals. Finally, I explore how various political regimes coped with these transportation networks and disease ecologies after the post-World War I dismemberment of the Ottoman domains. Based on archival research and powerful mapping tools like GIS, the product promises to illuminate the shared legacy of integration and disintegration in a broad swath of the Middle East now divided among different nation-states, bridging accounts of the late-Ottoman and interwar Middle East while also speaking to the developing field of the environmental history of disease. The project ultimately aims to highlight the unexpected connections forged in the process of modern states' attempts to simplify space, as well as the limits of these interventions.