The role of King Chitrasen (Mahendravarman) in the expansion of the Chenla Kingdom: A study of inscriptions and historical geography

This study explores the military campaigns of King Chitrasen, later known as King Mahendravarman, and his role in expanding the Chenla Kingdom through a geographical analysis of ancient inscriptions and the Least Cost Path (LCP) methodology. By integrating GIS-based LCP analysis, the research investigates the most probable military routes undertaken by King Chitrasen across present-day Thailand, Laos, and Cambodia. The analysis reveals multiple routes, divided into two main categories: paths traversing mountain passes of the Phnom Dong Rek mountain range and those following major river systems such as the Mekong, Mun, and Chi rivers. By examining the density of these routes, the study highlights a preference for river-based travel, especially along the Mun River, and emphasizes the practical constraints posed by natural obstacles such as the Khone Phapheng Falls, rapids, and sandbars, which likely prevented extensive river navigation. Therefore, King Chitrasen's forces likely traveled overland along the riverbanks, using waterways mainly as landmarks rather than for boat transport. Additionally, the strategic placement of inscriptions near key watersheds further suggests that King Chitrasen aimed to control transportation corridors and trade networks, rather than simply securing water sources for consumption. This research contributes to a deeper understanding of the role of geographic factors in the military and cultural expansion of ancient Southeast Asian empires, providing a new perspective on the interplay between territorial governance, military strategy, and landscape navigation.