Paul Vial, the author of “Nadokuse”, used a variety of different materials to reflect the social history and traditional culture of the Sani people from the end of the 19th century to the beginning of the 20th century. This book is a very precious historical document for the Shilin Sani people. The entire book is written in ancient Yi language. The author compares the ancient Yi language with the modern standard Yi language, analyzes the process and results of its evolution, and finds out the similarities and differences between the ancient Yi language and the standard Yi language.