Book excerpt: The Northern Wei was a dynasty which originated outside China and ruled northern China when the south of China was ruled by a series of dynasties which originated inside China. Both during the time that the Northern Wei dynasty was in power and over many centuries subsequently, the legitimacy of the Northern Wei dynasty has been questioned. This book outlines the history of the Northern Wei dynasty, including its origins and the history of its southern rivals; considers the practices adopted by both the Northern Wei dynasty and its rivals to establish legitimacy; and examines the debates which preoccupied Chinese scholars subsequently. The book casts light on traditional ideas about legitimate rule in China, ideas which have enduring relevance as tradition continues to be very significant in contemporary China.