This book is divided into two parts. The first part re-discussed the previous research on the history of relations between China and Central Asia. The second part studies some important topics that must be further scrutinized, such as Zhang Qian’s expedition to the West, Gan Ying’s expedition to the west, the commander of Wuji on the route to the Western Regions, Li Bo’s documents, and Turpan documents relaterd to the era; Starting from the research results of many researchers, we have come to different conclusions from those of our predecessors.