The collapses of several Neolithic cultures in China are considered to have been associated with abrupt climate change during the 4.2 ka BP event; however, the hydroclimate of this event in China is still poorly known. Based on stalagmite records from monsoonal China, we found that north China was dry but south China was wet during this event. We propose that the rain belt remained longer at its southern position, giving rise to a pronounced humidity gradient between north and south China.