The introduction begins with Ennin, the eminent Japanese monk who traveled to China in 838 with the last Japanese embassy to the Tang court. Then sojourning for nine years in China, Ennin witnessed that more-private forms of shipping and trade had already begun to displace the tribute system. Tracing Ennin’s experience in China, this chapter introduces three main themes of the book: Buddhist material culture and the monastic economy, trade via religious networks, and the relationship among monks, merchants, and the secular authorities. This chapter also explains the nontraditional sources that this book uses and the new readings of monastic records that it offers.