n the third century BCE, the Qin state emerged as the first great land-based empire in East Asia, but it quickly collapsed and was followed by the Han Empire. Han cultural identity became synonymous with “China,” including an elite culture built around the Confucian classics and a common culture based on family-organized ancestor worship. The Romans consolidated their authority around the Mediterranean world and defined an even more expansive identity—a new concept of “citizen” that eventually included all subjects of the Roman emperor. These empires made it possible for their subjects to live more peaceful and predictable lives than previously known. As both the Han and Roman empires fully exploited the ecological limits of their economic
