How did the climate of North Africa change between 10,000 B. C. and 1000 B. C.

in the middle of the Saharan Desert today there are pictographs of animals like those in the south of the continent ... that means at times in the past, the Sahara was green, and full of life ... Egypt is thought by some to have developed in this type of climate ... it has been getting much drier since after the last ice age ... there are many theories as to why its now a desert, but no one knows for sure why it is ...