Yiyi and Sihui, whose birth and death dates are unknown, were of Mongolian ethnicity (some say they were Hui people from the Yuan Dynasty), and lived approximately between the 13th and 14th centuries.

Hu Si Hui was a highly accomplished nutritionist, holding a significant position in the history of dietary therapy and medical development in our country. In the second year of Emperor Renzong of Yuan's Yanyou era (1315), Zhao Guogong Chang Pulanki served as the head of the Hui Zheng Yuan, overseeing matters related to serving the Empress Dowager. Hu Si Hui was selected around this time to serve as the imperial physician in charge of diet, attending to Emperor Renzong's mother, Empress Dowager Xing Sheng. During this period, he closely collaborated with Chang Pulanki in dietary therapy research. Later, he served in the imperial palace, attending to Empress Budashili as a dietary physician. Therefore, Hu Si Hui primarily served as the imperial dietary physician to the Empress Dowager and Empress in the Yuan court.

Hu Si Hui served as the imperial dietary physician for a long time, responsible for dietary regulation and health preservation in the palace. He emphasized the research and practice of dietary therapy and supplementation, which allowed him to timely summarize the dietary therapy experiences of previous imperial courts before Emperor Wenzong of Yuan. He also inherited the achievements in dietary therapy from famous materia medica works and the experiences of renowned physicians of previous generations, and paid attention to incorporating dietary therapy experiences from the daily lives of the common people at that time. It was under these circumstances that he compiled the renowned nutrition book Yinshan Zhengyao.