The Earth Ox border and the foothills demarcated the three tiers ethnic space regime in Qing Taiwan. It constituted governance deployment based on the territorization of ethnic groups—Chinese, Plain Aborigines (Cultivated Aborigines), and Mountain Aborigines (Raw Aborigines). This study explores the red (1750), blue (1760), purple (1784), and green (1790) border lines established in mid to late 18th century Taiwan to elucidate the shaping of the Cultivated Aborigines Buffer Zone that quarantined both Chinese and Raw Aborigines. Subsequent discussion focuses on how the quarantine of Chinese encroachment on aboriginal territories backfired and unintendedly led to illegal cross-border reclamation, the formation of frontier folk forces, and thus the eruption of an island-wide rebellion, the Lin Shuang-Wen revolt (1787-1788). Studying the reform of aboriginal policy in tandem with the establishment of the three tiers regime, this study employs the case of the Anli tribe to explore the incorporation and subsequent alienation of the plain aboriginal elite as collaborators of state power as well as stratification and, hence, factional strife within the plain aboriginal societies.