Some data from Ethiopia and the Horn of Africa indicate that drying there may have begun already 7,000-8,000 years ago or earlier. Reconstructions from Lake Abiyata in Ethiopia suggest that the end of the African humid period took the form of severe droughts rather than a gradual decrease of precipitation. Drying in Arabia commenced about 7,000 calibrated years ago and there are large disparities in the timing between various parts of Arabia but a tendency towards an arid climate between 6,000 and 5,000 years ago has been observed which continued until 2,700 years ago. In the Bale Mountains and the Sanetti Plateau of Ethiopia vegetation changes signalling a drier climate took place around 4,600 years ago.