Re-Viewing the Spatial Distribution of Prehistoric Sites in the Kegalle District of Sri Lanka: A GIS Approach

Geographic Information Systems (GIS)-based spatial analyses have become an important tool for prehistoric research globally. Sri Lanka holds a distinctive prehistoric record in South Asia, supported by extensive investigations. In contrast, the systematic applications of GIS analyses for prehistoric studies on the island are comparatively limited. This study examines the spatial distribution of prehistoric sites in the Kegalle district, where recent documentation suggests it differs from previous estimates. The study identified 16 new prehistoric sites, bringing the total to 22, including six already documented, representing the first GIS-based systematic expansion of the prehistoric site inventory in this district in six decades. Three analyses, Kernel Density Estimation (KDE), Least-Cost Path (LCP), supported by 3D terrain modelling and corridor analysis, were applied to examine site distribution and modelled movement potential. KDE results provided a preliminary spatial visualization showing higher site density around the Ma Oya basin and the Seethawaka Ganga, a tributary of the Kelani River basin; given the small sample size (n = 22), these patterns should be treated as survey coverage indications rather than confirmed settlement distributions. LCP indicated valley-oriented modelled movement potential, intermediate elevation site distribution and key topographic convergence points across the landscape. Corridor analysis identified low-gradient valley routes as probable topographic movement zones along the modeled least-cost paths. The integrated results suggest a preliminary pattern of valley-oriented site distribution and topographically favorable movement terrain concentrated around the Ma Oya and Kelani River basins, treated as exploratory spatial indications pending validation through future systematic survey and radiocarbon dating. This study presents one of the first systematic applications of an integrated GIS-based analytical framework for prehistoric spatial analysis in Sri Lanka, suggesting how such approaches can generate testable hypotheses and provide actionable guidance for future archaeological fieldwork in regions where comprehensive chronological data remain limited.