This is a unique work that combines the 20th-century history of all China's frontier lands in one book. "Recast All under Heaven" studies the outer regions of China (e.g., Mongolia, Xinjiang, and Tibet) in the twentieth century. By applying the two interpretative themes of 'frontier' and 'ethnicity' to the modern transformation of China, the book investigates 'domestic' and 'international' developments that helped transform the territorial domain and ethnic composition of the Chinese state from 'imperial' to 'national'. The book is based on published and archival information that became available in recent years, bringing 'frontier China' back into the mainstream of Chinese studies.