In early Chinese historical texts, Taiwan's Aboriginal peoples were called the Eastern Fan. Anthropologists further distinguished between the high mountain folk and the lowland Aboriginal peoples based on their population distribution.
The lowland Aborigines are made up of ten tribes, including the Ketagalan of Taipei, the Kavalan of Ilan, and the Taokas of the Hsinchu-Miaoli area. The Sirayans occupy, for the most part, the area made up by Tainan County, plus a swath extending down south to Pingtung. The name "Siraya" came from scholars during the era of Japanese occupation, who adapted the pronunciation of the Sirayan term for "I."
The Sirayans are the most numerous and powerful among the lowland Aborigines. The Sirayans are further subdivided into three tribal branches-the Siraya, the Makattao and the Taivoan. The largest branch-the Siraya-is further subdivided into the four settlements of Sincan, Mattow, Souloangh, and Backoloan.
The Backoloan people in Chiali, Tainan County, are the most powerful of the sub-tribal groups. Prior to the Dutch occupation of Taiwan, they even maintained their own kingdom. During the reign of the Qianlong Emperor during the Qing Dynasty, the Han Chinese began moving in in larger numbers, forcing the people of Backoloan to move. A portion of the Sirayans established the village of Kamasua in Tungho Village in Tungshan Township, Tainan County, which is the name it has been known by since then.