本文主要從歷史和文化動態對話的觀點，探討新竹苗栗山區賽夏族的族群邊界形塑與區域開發互動的關聯。透過歷史文獻和檔案、民族誌記錄、田野調查資料、和族人自我詮釋資料等綜合運用，一方面試圖檢視地區開發過程中，不同時代階段國家政策、地方資源、和人群互動的變化；另一方面也重新思考跨時代流動變化中反覆再現的「賽夏」特質，以及族群邊界形塑的可能機制。賽夏的例子，顯現出其族群邊界形塑過程，受到新竹苗栗交界山區的人群接觸、交易、移墾、殖民、軍事和行政區劃等各種政治經濟活動的影響，而日漸具體化和強化。但是，隨著社會生活環境的長時間發展變化，反而更凸顯出文化內在動趨力所引導的一些特定運作方向或原則；例如，「開山撫番」以來山區聚落的遷移模式與賽夏聚落性質、賽夏「家名」至「姓氏」的轉換等。總之，從動態對話的角度來思考族群邊界的流動，應該能夠更細緻的掌握歷史過程中人群互動關係的變化，以及理解當代與過去、內部價值觀念與外在刺激持續在實際生活中的對話與連結。

　　　　　 This paper aims at discussing the connection between the establishment of ethnic boundary of the Saisiat people and the development of the adjoining Nanzhuang area. By using historical materials, archives, ethnographies, field notes, and the Saisiat self-produced materials, on the one hand, we would like to examine the influences brought by the changes of state policies, exploitation of local resources and cross-cultural encounters in different times. On the other hand, we propose to investigate the constantly manifested "Siasiat-ness" features, as well as the possible institutions for shaping up the ethnic boundary under historical changes. In the case of Saisiat, it is shown that its ethnic boundary was influenced by the interactions with different groups of people who entered in the mountainous area of Xinzhu and Miaoli counties, and also reinforced by the outside economical and political impacts, such as trade market, land reclamation, military operation and administrative classification. Yet, in distinction to the external socio-economic changes, certain cultural codes and conceptual schema in the aboriginal society ought to be highlighted as extending agencies for integration. For instance, the special pattern of movement of the related aboriginal settlements since the "opening up the mountains and pacifying the aborigines" (kaishan fufan) scheme in the 1880s; and the systematic transformation from the aboriginal clan names to specific Han-Chinese surnames with similar meanings. In conclusion, to examine more subtle social changes in the historical processes, and to measure the ethnic boundary from a more fluid and dynamic point of view, we might have gained deeper understanding of the complicated dynamic interactions between different groups of people, and of the continuous discourse between the internal cultural values and external stimulants, as well as the past and the present.