Deciphering a Timeline of Demise at Medieval Angkor, Cambodia Using Remote Sensing

Sarah Klassen,Wayne Johnson,Roland Fletcher,Tiago Attorre,Ian Moffat,Rachna Chhay,David Brotherson

doi:10.3390/rs13112094

Abstract

The Greater Angkor Region was the center of the Khmer Empire from the 9th until the 13th to the 14th centuries CE, when it entered a period of decline. Many studies have suggested that the decline of Angkor was precipitated by several factors, including severe monsoons, geopolitical shifts, and invasions. In this paper, we use light detection and ranging and ground penetrating radar to investigate the possible intersection of two of these existential threats in one feature: the North Bank Wall. Our results indicate that this feature was designed with dual functionality of extending the urban area’s defenses to the east of Angkor Thom while maintaining the existing infrastructure for the distribution and disposal of water. These findings suggest that the North Bank Wall was built before the severe droughts in the mid-13th century. The timing of the construction indicates that the perceived need for additional security—whether from internal factional disputes or external adversaries—predated the final adaptations to the hydraulic network during the unprecedented monsoon variability of the 14th century. These results indicate that perceived political unrest may have played a more important role in the decline of the site than previously known.

Highlights

The Greater Angkor Region was home to an expansive urban site in central Cambodia that thrived from the 9th century until the 13th to 14th centuries CE, when it entered a period of gradual depopulation [1,2]
We explore the consequences of compounding forces on the settlement of Angkor and the decisions made to adjust and adapt pre-existing infrastructure to two of the challenges mentioned above: water management and defense against internal or external threats
Despite the general spatial characteristics of the North Bank Wall and the South Bank being identified in the 1930s, the functional relationship between the two was forgotten and only became apparent through the lidar-based digital terrain model (DTM) made available by Khmer Archaeological Lidar Consortium (KALC) in 2012 [28]

Summary

Introduction

The Greater Angkor Region was home to an expansive urban site in central Cambodia that thrived from the 9th century until the 13th to 14th centuries CE, when it entered a period of gradual depopulation [1,2]. Researchers have argued that the decline of Angkor was precipitated by many factors, including a series of severe monsoons and droughts that stressed the water management system [2,3,4,5], an increasing economic reliance on international trade [6,7], and foreign conflict and invasions [8]. We explore the consequences of compounding forces on the settlement of Angkor and the decisions made to adjust and adapt pre-existing infrastructure to two of the challenges mentioned above: water management and defense against internal or external threats. Old features related to water management were repurposed to provide defense [11,12].

Methods

Results

Discussion

Conclusion