This introductory chapter reviews the existing literature on the study of world history in China and offers a summary of key themes and main arguments of the book through a case study. Examining a conflict between a senior scholar Wu Mi and his junior colleagues in the early 1950s, it shows how the external influence from the communist state had transformed the relationship between different generations of scholars in academia under the newly established teaching and research unit system (jiaoyanshi). This case registers the widespread tension between state control and intellectual resistance in the emergence of the new research field of world history, which, as this Introduction argues, is an important key to understanding the development of world-historical studies. It not only affected the lives of individual historians but also gave way to the unintended rise of academic nationalism and the simultaneous marginalization of the discipline of world history. As the Introduction shows and the book will argue, this social and political dimension is a crucial factor in shaping the tension between national and world histories in China; and, in a subtle way, it was also a factor in the formation of twentieth-century Chinese identity.