The time span of the Dunhuang and Turfan Buddhist manuscripts runs from the 3rd to the 13th centuries which makes it extremely valuable for the study of the historical, cultural, and religious development of the Silk Road, as well as for the historical development of Chinese calligraphy. This study is based on Dual and Triple Evidence Methodology by combining Buddhist literary resources with Buddhist manuscripts found in Dunhuang and Turfan (3rd to 5th centuries), particularly, 49 pieces bearing inscriptions with an exact date, with which we attempt to trace and evaluate the evolutionary progression of the calligraphic styles used in copying Chinese Buddhist manuscripts before the Northern Wei period. The initial chapter discovers that the government official style of calligraphy, termed Standard Script 正書, was adopted and used in copying Buddhist manuscripts before the Northern Liang Dynasty (397-439 CE). The archaeological and literary evidence demonstrate that the appearance of Standard Script can be traced back to 171 CE, while Zhong You‘s 鍾繇 calligraphy was recognized as its highest level of achievement, which had tremendous influence on a number of early Buddhist scribes (e.g., Zhu Fashou 竺法首, Huisong 慧嵩, and Daoyang 道養 and the scribe Fanhai 樊海), and Chinese calligraphers (e.g., Wei Shuo 衛鑠 and Wang Xizhi 王羲之). Chapter 2 demonstrates that it was due to the contribution of Buddhist scribes with unique scriptural calligraphy, largely unknown in the history of Chinese calligraphy, that brought a substantial change in Chinese calligraphy with a strong Central Asian influence, leading to the appearance of the Northern Liang Style, the calligraphic style was mainly used in copying Buddhist scriptures and government official scripts during the Northern Liang period. Chapter 3 illustrates that it was due to the integration of the Northern Liang Style and the calligraphy of Wang Xizhi that brought about the evolution of calligraphy from the Northern Liang Style to the Weikai Standard Script 魏楷 in the Northern Wei 北魏 around the mid-5th century, which in turn laid a solid foundation and became the prototype of Standard Script in the Sui 隋 and Tang 唐 periods. From a study of the evolution of Standard Script in different periods before the Northern Wei period, we have successfully identified the main features of Zhong You‘s calligraphy, the Northern Liang Style and the Northern Wei Standard Script used in copying Buddhist scriptures in the Western Jin, the Northern Liang and the Northern Wei periods respectively. In Chapter 4, we have successfully applied our research results to date some previously undated Buddhist manuscripts.