Ethnic Distribution
The population of Sanyi Township comprises various ethnic groups, such as Hakka, Minan, and Mainlanders from external provinces. According to the survey in October 1957, there were 2024 households in total, with 63 Minan households, 1911 Hakka households (including 1863 families with Si-Rhan dialect and 48 families with Hoi-Liuk dialect), and 50 households with other provincial languages. Hakka dominates the area with 94.4% of the total population, while Minan and Mainlanders comprises 3.1% and 2.4% respectively. 

Because Sanyi is situated at the south tip of Miaoli County, neighboring Houli Township of Taichung County by the Daan River and connecting to Tongsiao Township with the Huoyan Mountain Range, residents in the Liyutan Village in the most southern area of Sanyi Township have established close relationship with the nearby towns above (most of them are dominated by Minan people). Therefore, 90% of the residents in Liyutan Village are Minan people. During the recent ten years, many Minan immigrants from other areas move to Shengsing Village for the business of wood sculptures. Besides, there are also some Mainlanders living in various villages in Sanyi. Most of the Hakka people in Sanyi can trace their origin back to Jiaoling County of Guangdong Province. Most of them speak Si-Rhan dialect. 

Most people in Sanyi can communicate with each other by using Mandarin, Taiwanese and Hakka languages. Especially in the Liyutan Village, most people can master Taiwanese and Hakka language pretty well.