Whilst Europe had been held firmly in the grip of the ice, the northern part of Africa was enjoying a mild tropical climate. The grassy plains and lush savannahs supported abundant herds of game, and following these herds many tribes of nomadic hunters. At the end of the Ice Age the rainfall decreased, and the region began to dry out, becoming in the end the world's greatest desert, the Sahara. The nomadic tribes were forced into the fertile valley of the one great river, the Nile.
The Nile is formed at Khartoum in the Sudan by the confluence of two rivers: the White Nile, arising from tributaries which reach all the way to Lake Victoria in central Africa, forms in the southern Sudan; the Blue Nile rises in the highlands of Ethiopia. The Nile also receives water from the Atbara, which joins it north of Khartoum.
The water level in the Nile underwent a very large seasonal variation. The Nile was lowest from April to June. In July the level began to rise as water from the Ethiopian summer monsoon entered the river via the Atbara. The Nile then rose 30 feet (9 metres) or more, beginning to flood in mid-August. The flood lasted until early September. It washed salts out of the soil, depositing a layer of fine silt, which over the ages built up a narrow but fertile flood plain extending from the first cataract to the sea. As the Nile entered the Mediterranean, it dropped further silt forming a fertile delta.
Sometime around 4500 BC the nomads, forced into the Nile valley by the drying out of the Sahara, began to set up villages and plant crops in the fertile silt. The crops were planted after the flood every year in October to November, and harvested between February and April of the next year. The villagers grew cereals, emmer for bread, barley for beer, lentils, peas, and vegetables such as lettuces, onions, and garlic. They reared livestock and poultry. By 4000-3500 BC these villages had spread over the whole of the Nile valley from present-day Aswan to the sea. A country had come into existence--Egypt.
The first historical king of Egypt was Menes (also called Aha), who ruled the combined kingdoms of upper and lower Egypt from his new capital at Memphis near present-day Cairo. According to legend, Menes introduced the picture writing or hieroglyphics into Egypt. The Egyptians wrote on