It goes without saying that in Ancient China interpreter was indispensable at the occasion of receiving foreign envoys or carrying out diplomatic negotiations. We can find a post of interpreter in the government of successive dynasties from the Han. This fact shows clearly that the demand for interpreter had long existed. Nevertheless, in remote boundary areas, where a lot of ethnic groups did not understand Chinese, we can imagine that smooth administrative activities could not be expected without the existence of an interpreter. As the system of the central government did not reach the boundary areas, local officials were forced to be prepared to deal with the affairs according to the special circumstances of the areas. In some cases, private interpreters which had been doing their business on their own risks could get an official license. This paper is intended as a historical socio-linguistic investigation of the real facts about the interpreters of the Tang-Song period especially for the Dunhuang and Turfan areas and the coastal areas in the East. In Turfan, the majority of the interpreters were Sogdians, and in the coastal areas in the East, the interpreters who served as an interpreter for the Japanese Buddhist pilgrims were Silla Koreans who had established their colonies along the coast of Shandong and the Chinese merchants from Mingzhou (Ningbo). Racial and ethnic background of each group of interpreters varies according to the area in which they were working. Still the essentials of the interpreters were inseparably associated with their business activity. Historical documents support the fact that they were merchants as well.
