Abstract: In historical records of the Yuan Dynasty （1279-1368）, information concerning whereabouts of Yinsheng Prefecture （jiedu） during the periods of the Nanzhao （738-902） and Dali （937-1253） kingdoms and its relationship with Kainan Prefecture is unclear. The region of Kainan Prefecture is often referred to as Yinsheng Prefecture and Kainan itself has virtually disappeared, a phenomenon that has survived history. As a matter of fact, both Kainan and Yinsheng prefectures existed, simultaneously but exercising jurisdiction over different areas. Then how did it come that Kainan Prefecture disappeared? It was the result of a decision made by the Dali Kingdom, on its wane, to move Yinsheng Prefecture to the region of Kainan Prefecture under pressure of the northward-advancing Dai people. According to some records, Yinsha Luodian was actually Yinsheng Prefecture （called fu at that time） in the Tang Dynasty （618-907） but later adopted a Dai name due to the eastward expansion of Si Kefa in late Yuan Dynasty, so people of the two following dynasties （Ming and Qing, 1368-1911） had no idea where it had been. That's why information about these two prefectures in question became unclear. Clarification of the historical evolution mentioned above of these two prefectures - Kainan and Yinsheng can tell us what and where they truly were and such an understanding can be of great significance to research of history, both that of Dali and other local historical identities.

Key words: Nanzhao Kingdom, Dali Kingdom, Yinsheng Prefecture, Kainan Prefecture, Yinsha Luodian, relocation, confusion