Book excerpt: Tracing journeys of Cantonese migrants along the West River and its tributaries, this book describes the circulation of people through one of the world’s great river systems between the late sixteenth and mid-nineteenth centuries. Steven B. Miles examines the relationship between diaspora and empire in an upriver frontier, and the role of migration in sustaining families and lineages in the homeland of what would become a global diaspora. Based on archival research and multisite fieldwork, this innovative history of mobility explores a set of diasporic practices ranging from the manipulation of household registration requirements to the maintenance of split families. Many of the institutions and practices that facilitated overseas migration were not adaptations of tradition to transnational modernity; rather, they emerged in the early modern era within the context of riverine migration. Likewise, the extension and consolidation of empire required not only unidirectional frontier settlement and sedentarization of indigenous populations. It was also responsible for the regular circulation between homeland and frontier of people who drove imperial expansion—even while turning imperial aims toward their own purposes of socioeconomic advancement.