This book addresses a largely untouched historical problem: the fourth to fifth centuries AD witnessed remarkably similar patterns of foreign invasion, conquest, and political fragmentation in Rome and China. Yet while the Western Roman Empire was never reestablished, China was reunified at the end of the sixth century. Following a comparative discussion of earlier historiographical and ethnographic traditions in the classical Greco-Roman and Chinese worlds, the book turns to the late antique/early medieval period, when the Western Roman Empire 'fell' and China was reconstituted as a united empire after centuries of foreign conquest and political division. Analyzing the discourse of ethnic identity in the historical texts of this later period, with original translations by the author, the book explores the extent to which notions of Self and Other, of 'barbarian' and 'civilized', help us understand both the transformation of the Roman world as well as the restoration of a unified imperial China.