Kisar, a small limestone island in southeastern Indonesia, holds archaeological evidence of human habitation extending back to the Late Pleistocene. Among its significant sites, Negeri Lama Purpura stands out as the largest fortification on the island. First occupied in the 14th to 15th centuries CE, the site exemplifies the strategic use of elevated locations for coastal defense and visibility. This early occupation, preceding European colonial expansion, indicates that security concerns were already prominent before the rise of the spice and slave trade. The transition from small band societies to more complex village communities in Island Southeast Asia during the 11th to 15th centuries likely stemmed from climatic factors and the growth of regional trade networks. Kisar's historical challenges, including overpopulation, drought, and deforestation, were exacerbated by limited natural resources. Despite these constraints, its strategic location—north of Timor and between the Lesser Sunda and Maluku Islands—enabled it to flourish as a regional trade hub and center for cultural exchange. Artefacts such as pottery, ceramics, and Indo-Pacific glass beads from Negeri Lama Purpura highlight Kisar's integration into regional and global maritime trade networks.