This article is a reconstruction of local Taiwan history that emphasizes the importance of combining both historical sources and ethnography. By formulating both types of data, I attempt to provide a new understanding of the socio-historical processes crucial to the development of the Sant'iao-Yenliao area prior to the 18th Century, a period Known as the "illiterate era." Inter-ethnic contact, Han village expansion, and other main historical events are but three of the distinct features of the history of the greater Tanshui-Sant'iao region. In this article, I argue that the last thirty years of the Ch'ien Lung reign era (1765-1795) comprise a crucial period in the historical development of the Sant'iao-Yenliao area. Prior to the 18th Century, local society, in which the Sant'iao aborigines were the dominant group, is properly chacterized as "illiterate." After that time, Han Chinese migrated into the area in large numbers, established villages and formed their own migrant society. From a macro perspective, I reconstruct the fundamental features of Sant'iao native society, describe its socio-historical phenomena, and analyze the mutual interaction of both throughout several periods: prehistory, the Spanish and Dutch occupations, and the early Ch'ing Dynasty.