The Effects of Climatic Oscillations (or the Lack Thereof) on Maritime Networks Between Angkor and China in the 14th and 15th Centuries

During the transition from the Medieval Climate Anomaly to the Little Ice Age (14th-15th centuries CE), Mainland Southeast Asia underwent climatic shifts that, from one historical perspective, culminated in the Angkor megadroughts and the subsequent fall of Angkor. This study examines whether such changes also altered the monsoonal wind regime enough to affect maritime connectivity between the Mekong River mouth and Quanzhou, China. Using the Digital Navigator, a sequential least-cost sailing model, together with the Last Millennium Ensemble (LME) paleoclimate dataset, we simulated weekly voyages in both directions from 1300 to 1499 CE and compared the results with LME-derived climate metrics. Within optimal sailing windows, voyage durations remained stable, showing no long-term trends and closely matching simulations based on modern wind data - even during the LME-identified megadrought. Variations appear driven by normal monsoonal dynamics: voyage durations from Quanzhou to the Mekong moderately correlate with the Oceanic Ni & ntilde;o Index. Outside the sailing windows, there are other moderate correlations with the aforementioned index and monsoon onset; however, these are periods when long-distance sailing was unlikely to be attempted. This study also illustrates the value of paleoclimate datasets for sailing simulations in archaeologically recent periods.