Forgotten Hills is a book about lost geographies. It is about how the subordination of mountainous Tibet to lowland China meant the erasure of the hills between, and how the legal, environmental, and social transformations of the eighteenth and nineteenth centuries hardened boundaries between Tibetan, Chinese, and Muslim peoples, obscuring the histories and practices that had bound hill folk together for generations. Wesley B. Chaney tells the story of this transformation by exploring small communities on the ferociously complex “mid-slope”—the hills along the northeastern edges of the Tibetan Plateau. Drawing from legal cases, genealogies, and Tibetan-language histories, Forgotten Hills illustrates how disputes over traditional landholding regimes erupted into violent conflict over resources and ethnic and religious identity. The ethno-politics that define modern China, this book reveals, arose from the legal disputes and everyday politics of the now forgotten hills.