On December 19, 1554, the members of Tenochtitlan's indigenous cabildo, or city council, petitioned Emperor Charles V of Spain for administrative changes "to save us from any Spaniard, mestizo, black, or mulato afflicting us in the marketplace, on the roads, in the canal, or in our homes." Within thirty years of the conquest, the presence of these groups in New Spain was large enough to threaten the social, economic, and cultural order of the indigenous elite. In Generos de Gente in Early Colonial Mexico, an ambitious rereading of colonial history, Robert C....