佛祖統紀 36.58

36.58

In the sixteenth year, a group of śramaṇas from Kaśmīra arrived in the region east of the Yangtze (Whenever a river flows from west to east, it faces east, takes west as its back, north as its left, and south as its right; therefore the south of the Yangtze should properly be called 'west of the Yangtze'. Since ancient times, it has been erroneously called 'east of the Yangtze' because people did not understand the meaning of front, back, left, and right. Calling Western Zhejiang 'Right Zhejiang' today suffers from the same error. This explanation was obtained from Master Ruzong). They translated three texts, including the San fadu jing (Tridharmaka-śāstra).