This article is a reconstruction of local Taiwan history that emphasizes the impor- tance 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 domi- nant 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.