The focus of this study is to present the recent changes in BB activity over PSEA by considering decadal changes, 5-year ensemble mean analysis, and long-term trends from twenty years (2001-2020) of Moderate Resolution Imaging Spectroradiometer (MODIS) active fire counts. The results revealed that overall springtime BB activity significantly decreased over the past decade (2011-2020) compared to the previous decade (2001-2010). Surprisingly, the individual monthly analysis revealed that BB activity over PSEA decreased substantially in March, whereas in April it increased significantly over the past decade (2011 to 2020). Further, 5-year ensemble means revealed, BB activity over northern PSEA in March sharply increased during 2006–2010, and moderately increased in 2011-2015 followed by a profound decrease in 2016-2020. Whereas, in April, the BB activity showed a pronounced increase in the 2011-2015 and 2016-2020 periods over northern Laos compared to the rest of PSEA. The observed changes in the BB activity are strongly reflected in the BB aerosols and gases. The MERRA-2 reanalysis total surface mass concentration-PM_2.5, BB black carbon, and MOPITT satellite observed surface carbon monoxide (CO) showed a significant decrease over northern PSEA in March and a strong enhancement was evident over northern Laos in April.  Finally, the trend analysis in BB activity shows a significant increasing trend over Laos and Cambodia, and a decreasing trend was found rest of the PSEA. These findings have important implications for future BB management strategies and regional climate in the PSEA region.