The frontier has long been a subject of interest for historians of the Ottoman Empire, whether their focus has been on the empire’s origins, its expansion, or its efforts to assert its sovereignty as it faced the threat of European imperialism.1 Gratien’s The Unsettled Plain shows a similar interest. It examines the rationale, implementation, and legacies of various Ottoman political projects that resulted in the environmental transformation of the swampy lowlands of Çukurova in southern Anatolia into an important center of commercial agriculture from the late nineteenth to the early twentieth century. The book spans the late Ottoman period, the tumultuous years of World War I, and the formative decades of the Turkish Republic. This important contribution to the steadily growing body of work about the Ottoman frontier draws heavily from the methods of environmental history.2For Gratien, the Ottoman frontier was not simply the sum of regions located along the empire’s geographical limits; rather, its defining features were its spaces, “pockets of transformation within the Ottoman provinces” (14). Moreover, that transformation manifested in at least three distinct ways to create a particular type of frontier experience during the late Ottoman period—new forms of state presence in rural settings (“frontiers of state”), the settlement of millions of people (“settlement frontier”), and human-nature interactions shaped increasingly by the forces of global capitalism (“ecological frontier”) (14). Although Gratien’s use of the term frontier throughout his book departs from the more common meaning of the term, this framing effectively “reveals a common story that was central to the remaking of Ottoman society” (15–16, 14). For example, it helps scholars to describe the process of environmental change in Ottoman lands with greater specificity than that captured by more conventional terms such as “provincial reform” (14).This framing device in place, Gratien narrates Çukurova’s environmental transformation as an Ottoman frontier with great clarity, carefully outlining what this process meant for the many generations of the region’s inhabitants. As Gratien demonstrates, seasonal migration was a key facet of life in Çukurova well-before it became Ottoman territory. The reason varied, but by the Ottoman period, one of the most important was health; locals regularly retreated to the pastures in the surrounding mountains to escape the malaria-prone swamps of the lowlands during the summer months. Seasonal migration also gave rise to a particular political order in Çukurova, whereby the Ottoman state delegated the task of securing the obedience of the region’s nomadic population to local elites in the nearby mountains. By the second half of the nineteenth century, however, the Ottoman government sought to curb the power of these elites as part of a broader centralization of the empire. It also began to see pastoralism as at odds with its vision of Çukurova as a potential center for commercial agriculture in the future. Thus, from the second half of the nineteenth century forward, the Ottoman government worked to settle not only pastoralists in Çukurova but also refugees in hopes of tapping into the region’s agrarian potential, which Ottoman officials often compared to that of Egypt. Among the many unfortunate consequences of this ecological transformation was the continued exposure of the region’s inhabitants to malaria, which remained a threat during World War I and after the establishment of the Turkish Republic.Historians of the Ottoman Empire and environmental historians in general will certainly recognize the importance of The Unsettled Plain. But non-specialists interested in interdisciplinary approaches to the study of history also stand to benefit from it. Gratien includes several citations from scientific studies that further deepen readers’ understanding of Çukurova’s environmental history, especially as it concerns the types of mosquitos that transmit malaria and the conditions under which they thrive (37, 159). Indeed, Gratien’s book is just the latest to demonstrate how sophisticated the field of Middle East environmental history has become.