Fiefs and Vassals has changed our view of the medieval world. It offers a fundamental challenge to orthodox conceptions of feudalism. Susan Reynolds argues that the concepts of the fief and of vassalage, as understood by historians of medieval Europe, were constructed by post-medieval scholars from the works of medieval academic lawyers and tha they provide a bad guide to the realities of medieval society. This is a radical new examination of relations between rulers, nobles, and free men, the distillation of wide-ranging research by a leading medieval historian. It has revolutionized the way we think of the Middle Ages.

中國中古時期的「封建」，與西周的「封建」，乃至於現代認知的封建，實為不同的概念；本書對於魏晉南北朝的封建制度與政治秩序，有深入的分析與探討。
本書以爵制為研究重心，探討中國中古時期封建的意涵，以及爵制與政治秩序的關係。中國中古封建體系，名義上遵循西周封建制度，實際是經由戰國兩漢以來儒生、士人不斷追溯重構，形塑出一套關於西周封建的「歷史記憶」。中國中古封建以王爵與五等爵替代西周諸侯，建立天子冊命諸侯統治封國的架構，並藉由儒家經典與漢魏故事，制定專屬諸侯的「開國」制度與「茅土」儀式。各王朝也藉由冊封周邊勢力，建構天下秩序，彰顯政權居於天下共主的地位。本書不僅關注封建體制的具體實踐方式，也重新考察中國中古時期的政局與制度變遷。