<p>Modern instrumental observations indicate increasing drought in monsoonal mainland Southeast Asia and more frequent extreme precipitation events in arid Central Asia. These changes underlie the emergence of atypical hydroclimate extremes that deviate from the mean climate background, posing severe threats to local agriculture and ecosystems. However, it remains unclear whether these new extremes differ from those arising from natural climate variability and whether their recent co-occurrence is coincidental or dynamically linked through large-scale ocean–atmosphere interactions. Here we use palaeoclimate reanalysis that combines proxy records spanning the past millennium and climate models to show an unprecedented increase of intense dry extremes in mainland Southeast Asia and wet extremes in Central Asia since pre-industrial times. We further demonstrate that their co-occurrence is associated with coupled sea surface temperature variability in the Pacific and Indian oceans, which modulates atmospheric circulation and moisture transport, producing contrasting precipitation anomalies between the two regions. Multimodel simulations of the past millennium, the historical period and future warming scenarios consistently reveal a robust coupling between precipitation in Central and Mainland Southeast Asia and its linkage to oceanic forcing. This persistent large-scale mechanism provides a physical basis for anticipating synchronous hydroclimate extremes across geographically distant regions of Asia.</p>