The sources of the Nile river are the rivers While Nile Blue Nile and the Atbara river. The White Nile comes from Lake Victoria and other smaller lakes south of Egypt. This source is consistent in its flow. The annual flooding of the Nile is caused by the rains in Ethiopia from June to October which cause the Blue Nile and the Atbara to flow with much more water. 20,000 to 12,000 years ago during the last ice Age in Europe was a very dry time in the Sahara and Egypt. Starting about 12,000 years ago the rainfall increased significantly and 10,000 to 8500 years ago the rains were so heavy that it is called the Wild Nile time and it appears that there was no one living in the Nile region due to the dramatic flooding. People at this time were living in the area which is now the Sahara because there were river systems and lakes which are created grasslands. It was not until the massive rains calmed down that agriculture began to appear in the Nile region around 5500 – 4000 BCE.

(The Great Courses – The Origin of Civilization)