Societal response to monsoonal fluctuations in NE Thailand during the demise of Angkor Civilisation. (October 2017)

• Record Type: Journal Article
• Authors: Yamoah, Kweku Afrifa; Higham, Charles FW; Wohlfarth, Barbara; Chabangborn, Akkaneewut; Chawchai, Sakonvan; Schenk, Frederik; Smittenberg, Rienk H
• Is Part Of: Holocene. Volume 27:Number 10(2017)
• Page Start: 1455
• Page End: 1464
• Publication Date: 2017-10
• Subjects: δ13Cwax -- δDwax -- Angkor Civilisation -- Lake Pa Kho -- northeast Thailand -- Southeast Asia -- wetland; Geology, Stratigraphic -- Holocene -- Periodicals; Paleoclimatology -- Periodicals; 333.7
• DOI: 10.1177/0959683617693900
• Languages: English
• ISSNs: 0959-6836

Abstract

This paper investigates the possible social responses to changes in the strength of the southwest monsoon in northeastern Thailand during the currency of the Angkor civilisation. These assessments are based on hydrogen and carbon isotope records of leaf waxes (δDwax and δ 13 Cwax ) from a 2000-year-long wetland sequence of Pa Kho in northeastern Thailand, a region that formed the northern boundary of the Angkor Kingdom. Our data indicate anthropogenic flooding of the Pa Kho wetland through the control of water through dam construction from c. AD 1300 in response to the fluctuating strength of monsoon rains. δDwax, a proxy for regional hydroclimate variability, corroborates pre-existing evidence that increased summer monsoon rains, which supported the expansion of the agrarian economy, aided the rise of the Angkorian Empire whereas extreme drought contributed to its demise. Interestingly, our δDwax record shows already a gradual decreasing monsoon intensity from c. AD 1000 onwards, although Angkor's prosperity reached its peak at c. AD 1200. We suggest that the complex hydrological system established under royal patronage at Angkor provided a resilient buffer against short-term monsoon fluctuations. The long-term decline in monsoon rains over a ~300-year period, combined with ongoing urbanisation, may have stretched the hydrological systems to their limit. We suggest that this was a major factor that contributed to the demise of Angkor in the mid-15th century.