INTRODUCTION “The Western Regions” is a geographical concept as seen in the “official history books” of the Western Han 漢, Eastern Han 漢, Cao-Wei 曹魏, Western Jin 晉, and Northern and Southern dynasties, which refers to a vast region to the west of the Yumen 玉門 and Yang 陽 Barriers under most circumstances, but sometimes refers to the Tarim Basin and its surrounding area. In other words, it had both a broad sense and a narrow sense. In this book, “the Western Regions” is used in the broad sense, but the focal point of the study is located in the region which is called Central Asia today, especially to the east of the Pamirs. This was determined by the actual relationship between the Western Regions and the Western Han 漢, Eastern Han 漢, Cao-Wei 曹魏, Western Jin 晉, and Northern and Southern dynasties. The study of the history of the relationship between the Western Han 漢, Eastern Han 漢, Wei 魏, Jin 晉, and Northern and Southern dynasties and the Western Regions is an important topic in the study of ancient Chinese history; its significance is self-evident. The task of this book is to ascertain the related historical facts as far as possible. The facts can be summarized as follows: The purpose of the Western Han 漢, Eastern Han 漢, Cao-Wei 曹魏, Western Jin 晉, and Northern and Southern dynasties in managing the Western Regions can be summed up with the statement “it would be possible to extend [Han 漢] territory for 10,000 li 里. With [the help of] a series of interpreters, those whose customs were exotic could be brought to court, and imperial power and prestige could be exercised throughout the area within the Four Seas”. It is quite obvious that this purpose was mainly political. In contrast, the purpose of the various states of the Western Regions in contacting the Western Han 漢, Eastern Han 漢, Cao-Wei 曹魏, Western Jin 晉, and Northern and Southern dynasties was primarily economical, namely the “wish to exchange their goods and conduct trade”. Of course, they were also the interested in absorbing the advanced culture of the latter, namely they “admired and took pleasure in the Middle Kingdom”. In addition, the various states to the east of the Pamirs also sought protection from the depredations of the nomadic tribes beyond the Great Wall.