Gyounen (凝然, 1240-1321), a Japanese monk, wrote two volumes of Hasshu koyo (《八宗綱要》), edited in an question-and-answer way, to introduce how Buddhism went from India to China and then to Japan. In the books, Nantorikushu (南都六宗) and Heian ni shu (平安二宗) are discussed, with an appendix in which he also wrote about how Zenso (禪宗) and Jodo shu (淨土宗) in Sung Dynasty were transmitted into Japan. Basically, Hasshu koyo is a concise edition of China-Japan Buddhist Schools’ History. Since TOKUGAWA (德川) age, Hasshu koyo has become the fundamental book for Japanese to understand China Buddhism.
At the end of Quing Dynasty, Yang Ren-Shan (楊仁山), with the help from his relatives and friends, brought a large number of the books of China Buddhism, which have been passed to Japan. Hasshu koyo was one of the books he got at the time. After reading the book, Yang Ren-Shan started to write the essay to argue the questions of China Buddhism sects, which is viewed as the first paper of this field. And as a result, Hasshu koyo was widely known by China Scholars after then.
At the beginning of the interaction, Japan Buddhism groups set Hasshu koyo as the textbook to learn about China Buddhism History. And because of its conciseness in the development of the Buddhist schools, it should also have great value in studying the modern China Buddhism. As early as in the 1930s, there were scholars in China referring to Hasshu koyo to write the history of China Buddhism, and therefore it is no doubt that it has played a big role in the Buddhist debate in China now.