This chapter explains how the book departs from earlier studies of ancient long-distance trade in taking the academic traditions of Global history and Environmental history as its points of departure, aiming to see beyond states and empires as the dominant analytical categories, and to appreciate the role of the natural environment in enabling, shaping and restricting production, movement and exchange. The chapter then introduces three concepts that serve to integrate the narrative: cities, trade and networks. After outlining key scholarly debates on these topics within archaeology and ancient history, it is argued that the growth of urbanism, long-distance trade and connectivity were three central phenomena of Afro-Eurasian history in the so-called Long Classical Millennium (fourth century BCE to eight century CE), and that historical network theory provides tools that allow us to study them within a unified analytical framework.