Increased variability in precipitation may have preceded the end of the AHP; this is commonly observed before a sudden change in climate. In Gilf Kebir, between 6,300 and 5,200 years ago apparently a winter rainfall regime became established as the AHP ended. Later fluctuations in climate that produced brief humid spells also took place, such as a moister period between 500 BCE - 300 CE in Roman Northern Africa and along the Dead Sea and an earlier one 2,100 years before present in the western Sahel.