At http://af.reuters.com/articlePrint?articleId=AFJOE64NO9L20100524 May 24th … archaeologists have found prehistoric rock art in a remote cave in Egypt which included dancing figurines and strange headless beasts, and they are being studied in order to find clues to early Egyptian civilisation. Some 5000 images have been found in the cave in the desert near the SW border with Libya and Sudan. The rock art has been dated to about 8000 years ago – 6000BC. In context seasonal rainfall was endemic in the Sahara from 8500BC which created a savannah environment of the kind that now exists south of the desert zone. They continue by saying that by 5300BC rainfall had declined and humans retreated into highland zones and by 3500BC even these groups of people disappeared. In practise, communities continued to exist in the highlands for much longer but in a general overview the main thrust of human occupation of the Sahara had come to an end. Hence, the argument is that as the Sahara dried out people moved into the Nile Valley, a consensus opinion that has dominated archaeology in the region for many years. In this article it is described as a ‘mass exodus’ of people and we may note the appearance of the Pre-Dynastic peoples correspond roughly with 5300BC (for whatever reason). However, at the same time it is admitted the ‘mass exodus’ occurred step by step as the desert didn’t just suddenly appear but the savannah gradually dried out – to be revived on a number of occasions only to dry out once again, each time to a greater degree. It is not clear how much this process of desertification is theorised from the Milankovitch model – generated by computer simulation, and how much is due from evidence on the ground. The Milankovitch model would demand a gradual process of desertification as a result of decreasing precipitation but there is plenty of evidence that intermittent cold dry spells punctuate the climate of western Asia and Egypt during the Holocene at large, and this may account for the step by step up and down evidence that probably exists but is usually not mentioned. However, the transition from hunter gatherer (as the rock artists are described) to farmers (that exploited the Nile Valley in the 4th and 3rd millenniums BC), is not adequately understood and appears to indicate that more than one group entered Egypt from the south.