'Caste' is today almost universally perceived as an ancient and unchanging Hindu institution preserved solely by a deep-seated religious ideology. Yet the word itself is an importation from sixteenth-century Europe. This book tracks the long history of the practices amalgamated under this label and shows their connection to changing patterns of social and political power down to the present. It frames caste as an involuted and complex form of ethnicity and explains why it persisted under non-Hindu rulers and in non-Hindu communities across South Asia.