Abstract Mainland Southeast Asia is located on the moisture transport route of the Indian summer monsoon (ISM) where hydroclimate records from speleothems have rarely been investigated. Here, we present a new multi-proxy (δ18O and δ13C values, trace element concentrations, and grayscale values) data set of stalagmite KPC1 from Khao Prae cave in western Thailand spanning the last 1400 years (500–1900 CE; the Common Era). These multi-proxy data reveal a high variability between the wet and dry periods during 500–850 CE and 1150–1300 CE, stable climate conditions during 850–1150 CE, and overall dry conditions since 1300 CE. The δ13C values, trace elements concentrations, and grayscale values show centennial-scale fluctuations, which were probably driven by local hydrological processes. In contrast, variations in the stalagmite δ18O values reflect integrated changes in rainfall amount from the ISM. The KPC1 record agrees with other speleothem δ18O records of Southeast Asian summer monsoon from the last millennium, as well as the lake multi-proxy and tree-ring PDSI data from Mainland Southeast Asia, but diverges from records from the Indo-Pacific equatorial regions and the western Pacific. We conclude that hydroclimate variability at the western side of Mainland Southeast Asia is mainly driven by changes in moisture transport of the ISM. On socially relevant timescales, the KPC1 data set shows that a period of stable rainfall (850–1150 CE) coincides with the early success of the early empires (e.g., Pagan, Angkor, and Dai Viet) in Mainland Southeast Asia. In line with previous studies in the region, we speculate that the high variability in rainfall between 1150 and 1300 CE and droughts during 1300–1550 CE played a significant role in the demise of ancient societies in Southeast Asia.

中文翻译：

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过去 1400 年泰国西部的水文气候变化

摘要 东南亚大陆位于印度夏季风 (ISM) 的水分输送路线上，很少对洞穴水文的水文气候记录进行调查。在这里，我们展示了过去 1400 年（公元 500-1900 年；共同时代）来自泰国西部考普拉洞穴的石笋 KPC1 的新多代理（δ18O 和 δ13C 值、微量元素浓度和灰度值）数据集. 这些多代理数据揭示了公元 500-850 年和公元 1150-1300 年的干湿期、公元 850-1150 年的稳定气候条件以及自公元 1300 年以来的总体干燥条件之间的高度可变性。δ13​​C 值、微量元素浓度和灰度值显示百年尺度波动，这可能是由当地的水文过程驱动的。相比之下，石笋 δ18O 值的变化反映了 ISM 降雨量的综合变化。KPC1 记录与上一千年东南亚夏季风的其他 speleothem δ18O 记录以及来自东南亚大陆的湖泊多代理和树轮 PDSI 数据一致，但与来自印度太平洋赤道地区和西太平洋。我们得出结论，东南亚大陆西侧的水文气候变化主要是由 ISM 水分输送的变化驱动的。在与社会相关的时间尺度上，KPC1 数据集显示稳定降雨时期（公元 850-1150 年）恰逢东南亚大陆早期帝国（例如异教徒、吴哥和大越）的早期成功。根据该地区先前的研究，