Asian dust storms influence climate, air quality, and nutrient supply, yet debate persists over whether their activity peaked during the cold Little Ice Age (LIA, similar to 1550-1850 CE) or in the warmer, land-use-intensive modern era. Existing reconstructions derive mainly from loess, lake, and ice-core archives; these capture aspects of dust activity but suffer from chronological uncertainty. High-resolution downwind marine records at subannual scales remain scarce. We analyzed monthly barium-to-calcium (Ba/Ca) ratios in a Porites coral core from the Xisha Islands in the South China Sea (SCS), generating the first monthly resolved marine record of downwind dust-associated aerosol delivery to the SCS during 1816-2014 CE. After excluding the influences of fluvial input, groundwater, upwelling, sediment resuspension, biological processes, and skeletal growth-rate effects, we interpret the March-May Ba/Ca spikes as signatures of Ba-rich aerosols delivered during spring dust activity. A Pettitt change-point test identified 1870 as the boundary between two regimes: during 1816-1870, the mean spring Ba/Ca was 14.69 mu mol mol(-1) (vs. 10.47 mu mol mol(-1) thereafter), the variance was greater (3.44 vs. 2.24), and extreme events (>16.49 mu mol mol(-1)) occurred in 31.5% of years (vs. 1.5% after 1870); all differences are significant. The post-1870 decline in dust delivery parallels a weaker Siberian High, wetter upwind conditions, and fewer El Ni & ntilde;o events, with no sustained anthropogenic increase in long-range dust delivery to the SCS. These findings underscore climate forcing as the primary regulator of long-range dust export and provide a precisely dated benchmark for testing aerosol-climate models and future dust-climate feedbacks.