The thesis, "Chinese Zen Buddism in Tibet", concerns mainly the incident of the Tibet controversy，or Sangye controversy，which occurred between 792 and 794 A.D. during the reign of chisongdenzan，in an effort to understand the spread of Buddhism from the sixth to the eighth century in Tibet，with specific attention addressed to the development of the zen Buddhism from the China proper.
The Tibet controversy involved confrontations of theories and believes in Lasa between a sect of Longshu Buddhism，which derived from India, and zen Buddhism from the China proper. This was the time after the establishment of the Tufan kingdom in Tibet. Both due to the geographical spread of the kingdom to Changan，the capital of the Tang dynasty and the center of Tang Buddhism，and to the contacts with the four military forts of Anxi (literally，the suppressed West)，a portion of the Tufan Kingdom began interested in Buddhism. This study thus will begin with a survery of the various sects of Buddhism in Tibet，including the zen Buddhism from the China proper; the latter deserves our particular attention，as it was so powerful as to triger the Tibet controversy.
From what sect of Buddhism did the zen Buddhism which prevailed in Tibet at that time actually develop? For this, I suggest，one has to look into Mokeyan's The Diologue of Sudden Enlightenment: Politics and Theories in Mahayana Buddhism (dunwu dasheng zhengli jue) to find the answer; Mokeyan was one of the key figures in the incident. From there, one then moves to examine the zen Buddhism represented by Mokeyan; what sect did he belong to? Were there other sects of zen Buddhism from the China proper other than that of Mokeyan? If so，what sects were they? Via what means and by what routes did they spread to Tibet? In terms of this incedent, why was the zen Buddhism defeated? Were there political factors involved? Moreover，after the incident，how was the influence of the zen Buddhism of the China proper in Tibet? These are issues to be explored in this study.
