This book, as part of a book series on migration in Chinese history, explores migration that took place in the Liao, Song, Jin and Yuan dynasties. This series is a complete, systematic general history on migration in China, the first of its kind both in China and abroad. Though it falls into the category of East Asian History, it is actually an interdisciplinary academic work that looks into not merely history but also culture, customs and historical geography. For the migration of each sub-period, the book seeks to identify the causes, participants, times, destinations, origins, routes and directions of migration, as well as the process of settlement and effect. It also tries to make quantitative analysis and sum up underlying patterns. This book draws evidence from a broad spectrum of sources, including literature, social customs and linguistics, in addition to official histories. It is not only a monograph on historical migrations in China, but also offers an opportunity of interpreting historical transformations from the perspective of migration. This book is intended for academic readers who study migration, Chinese history and historical geography, as well as the general public who loves Chinese culture and wishes to view Chinese culture from a novel perspective.