This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book explores one aspect of this transformation in the study of Chinese history. It focuses on one specific area of Ming history, and indeed in a sense on a specific discovery. The book also focuses on a different question: the impact and interaction of Ming military institutions with Chinese local society, and the long-term consequences of the relationship. It shows how official military cults and rituals proved inadequate for the religious needs of Guard residents, who on the one hand incorporated cults from the surrounding area into their own religious practice and on the other provided religious resources that came to be incorporated into the practices of the surrounding area. The book illustrates another form of localization, involving the interaction of the imperial state, local communities, and the military institutions that mediated between them in the production of local history.