Drawing on abundant historical sources and rigorous research, this book revisits the question of aristocratic clan politics in medieval Chinese history. It argues that the aristocratic clan politics commonly attributed by Chinese and foreign scholars to the Wei, Jin, and Northern and Southern dynasties in fact existed only during the Eastern Jin. Aristocratic clan politics was an abnormal form of imperial rule that emerged under particular historical conditions; it was temporary and transitional, taking the form of joint rule by aristocratic clans and the emperor. Avoiding the conventional approach of defining aristocratic clans through marriage and official careers, the book offers incisive insights into this important subject in the history of medieval Chinese politics and is of considerable academic value.