This book, first published in 1940 by the American Geographical Society in its International Research Series, has remained the classic study of the Central Asian region of China from ancient times to the period immediately prior to World War II. In particular, Lattimore examines the effect of the region's frontier status on its history and development. The book is based on extensive travel and research throughout the region as well as on exhaustive reading in Chinese, Russian, Mongolian and English sources.