本文探究乾隆年間臺灣歷次劃定邊界及清釐沿邊民番地界的治理實作，以說 明清代國家權力如何進行族群空間治理的策略部署。清廷自乾隆10 年起順勢利用 熟番因海岸平原土地大量流失而往沿山地帶遷移的趨勢，修改原「界內漢人熟番 ／界外生番」簡單二分式的族群空間分布，試圖形構三層式族群空間體制（三層 制），以熟番族群居間形成夾心層地帶，藉以區隔內山生番與海岸平原的漢人。該 體制透過劃界遷民加強族群隔離，並操弄族群歧異以阻遏漢人進入界外開墾、聚 民為亂。經過一段嘗試錯誤的過程後，三層制終於在乾隆中葉（乾隆25 年左右） 以一連串更加嚴密、周詳的軟硬體措施──土牛界、番通事、隘番制、熟番地權 保護、理番同知衙門設立──加以落實。然而，逆勢阻擋漢人移民開墾界外土地 及利用山林的趨勢，在治安上卻造成適得其反的效果。事實證明，漢人越界私墾 大勢所趨，不僅難以阻阨，而且還發展出挑戰國家權力的界外勢力，引發（林爽 文事件等）動亂。透過比較乾隆49 年紫線界與前後（藍綠線）邊界的劃定及歷次 沿邊民番土地（所有和租佃）關係的重安排，筆者試圖說明三層制的形構與轉型， 以及闡釋清廷對臺族群空間治理的策略部署如何相應地從強調族群地帶區隔轉化 為以屯番制積極利用熟番武力。

This study explores the boundary drawings and arrangements of ethnic land tenure along the frontier area to explicate the ethnic-spatial deployment by the state power in Qing Taiwan circa1745-1790 (＂Qianlong era＂). It was the state's intention since 1745 to initiate a three-tier ethnic-spatial regime, through creating a buffer zone at the foothill boundary separating head-hunting mountain aborigines and coastal-plain Chinese settlers with plain aborigines sandwiched in between. The aim was to quarantine Chinese reclamation of aboriginal land and preempt security harass beyond the borderline. To achieve this aim, a plain aborigine border guard (＂ai fan＂) system was implemented concomitantly, with the reallocation of plain aborigine land rights to the buffer zone for segmentation as well as providing rations to border sentry posts. However, the state's effort to counter cross-border reclamation and thus prevent Chinese encroachers from developing into unruly force proved in vain. Even worse, it backfired, as shown in the Lin Shuang-wen revolt (1786-1788). With the aborted purple borderline of 1784 as the benchmark, a comparison of the pre- and post-1784 boundary redrawings, blue borderline of 1760 and green borderline of 1790 respectively, as well as concomitant reallocations and rearrangements of aborigine land rights indicates a transformation of the three-tier ethnic-spatial regime, as witnessed in the shift of governance rationality from quarantine to active alliance with plain aborigines through fostering its militia forces (＂tun fan＂).