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Understanding the variability and related dynamic mechanisms of the Indian summer monsoon evolution over the past millenniums is crucial for disaster prevention and mitigation in the context of strengthening global warming. Here, we present a high‐resolution hydroclimate reconstruction over the past 3110 years in northwestern Yunnan Province, southwestern China, based on grain size analysis using the End‐member modeling algorithm and other environmental proxies. The results indicate that the temperature in northwestern Yunnan Province generally decreased since 3110 cal. yr BP, aligning with other temperature records on regional and global scales. Precipitation in the study area remained relatively stable before 1000 cal. yr BP, but exhibited an obvious out‐phase change compared with the temperature records over multidecadal to centennial timescale. While after 1000 cal. yr BP, the precipitation steadily increased, revealing the hydroclimate pattern of notably dry Medieval Warm Period (MWP) and relatively wet Little Ice Age (LIA) in the study area. The decoupling combination of temperature and precipitation spanning the MWP and LIA in southwestern China contrasts with that in the East Asian summer monsoon area and the Indian subcontinent which is also controlled by the Indian summer monsoon, indicating the spatial heterogeneity of precipitation in the Asian summer monsoon region. The discussion about dynamic mechanisms points out that solar activity emerges as a significant factor influencing regional temperature changes, and El Niño‐Southern Oscillation and Intertropical Convergence Zone migration jointly impact the precipitation change in the study area and the hydroclimate discrepancy in the Asian summer monsoon region. Plain Language Summary: Knowledge of the Indian summer monsoon evolution over the past millennium is vital for addressing the challenges posed by global warming. In this study, we present a high‐resolution hydroclimate reconstruction covering the last 3110 years in northwestern Yunnan Province, southwestern China. Using the End‐member Modeling Algorithm and multiple environmental proxies, we found a general temperature decrease since 3110 cal. yr BP, consistent with global and regional trends. Before 1000 cal. yr BP, precipitation in the study area remained stable but showed a distinct antiphase pattern with temperature variations over multidecadal to centennial timescales. After 1000 cal. yr BP, precipitation steadily increased, revealing a notably dry Medieval Warm Period (MWP) and a relatively wet Little Ice Age (LIA). The decoupling of temperature and precipitation during the MWP and LIA in southwestern China contrasts with the East Asian summer monsoon and the Indian subcontinent, highlighting the spatial heterogeneity of precipitation in the Asian summer monsoon (ASM) region. Our discussion on dynamic mechanisms highlights the significant role of solar activity in regional temperature changes and the joint impact of El Niño‐Southern Oscillation and Intertropical Convergence Zone migration on precipitation in the study area and the broader ASM region. Key Points: Precipitation change in the study area was indicated by the relative proportion of end membersDecoupling warming and monsoon precipitation in northwestern Yunnan Province was revealedEl Niño‐Southern Oscillation and Intertropical Convergence Zone migration jointly impact the hydroclimate discrepancy in the Asian summer monsoon region [ABSTRACT FROM AUTHOR]

The tropical mountainous area of the southeastern Tibetan Plateau (TP) is a hotspot of ecological environment research because of its rich biodiversity. However, limited knowledge regarding modern pollen rain within this area has impeded further investigation of eco-environmental evolution using the pollen record. We collected 62 modern pollen samples from lowland tropics to the subalpine region (740–3550 m a.s.l.) in Medog County, located in the southeastern TP, and performed pollen analysis. Cluster analysis, redundancy analysis, variance partitioning analysis, and boosted regression trees were employed to investigate the relationship between pollen and vegetation/climate. Additionally, Hill numbers (N0, N1, N2) and specificity–occupancy plots were utilized to explore plant diversity. The results indicate that modern pollen rain in Medog reflects well the current characteristics of the vegetation, encompassing both primary and secondary features. Pollen of Cyclobalanopsis, Tsuga and Abies, which are dominant components of the primary vegetation above 2100 m a.s.l., can serve as indicator species for paleovegetation reconstructions. Mean annual precipitation is the most important climatic determinant affecting pollen distribution. Pollen indices reveal that the plant diversity in this study area has a bimodal pattern of 'relatively high–low–highest–low' with increasing altitude. The plant diversity above 2100 m a.s.l. is mainly decided by primary vegetation, whereas below 2100 m a.s.l. it can be explained by the intermediate disturbance hypothesis. Furthermore, it is advisable to exercise caution when dealing with arboreal pollen evenness in open mountainous environments due to the increased potential pollen source area caused by valley wind. [ABSTRACT FROM AUTHOR]