The correct reading of Tocharian documents is necessary in order to comprehend Tocharian Buddhism. However, almost all Tocharian documents are so fragmentary that it is difficult to decipher them. When words or sentences are conjectured in lacune in order to identify the fragments with some other already known texts, while this may allow us to “read” the text, the results are not academically significant. The same thing is done in other fields. After examining relating data, it is important to research them diachronically and synchronically.