In 1644, the Manchus, a relatively unknown people inhabiting China's northeastern frontier, overthrew the Ming, Asia's mightiest rulers, and established the Qing dynasty, which endured to 1912. From this event arises one of Chinese history's great conundrums: How did a barely literate alien people manage to remain in power for nearly 300 years over a highly cultured population that was vastly superior in number? Drawing on recent critical notions of ethnicity, the author explores the evolution of the 'Eight Banners', a unique Manchu system of social and military organization that was instrumental in the conquest of the Ming. Their power derived not only from the acceptance of orthodox Chinese notions of legitimacy, but also, the author suggests, from Manchu 'ethnic sovereignty', which depended on the sustained coherence of the conquest group.