The Nile Valley and Its Civilizations

The Nile is, by most measures, the longest river in the world at roughly 6,650 kilometers, formed by the confluence of the White Nile, which rises from Lake Victoria in East Africa, and the Blue Nile, which rises from Lake Tana in the Ethiopian Highlands and joins the White Nile at Khartoum in Sudan. The Blue Nile and its tributary the Atbara supply the great majority of the river's water and virtually all of its fertile silt, carried north across roughly 1,100 kilometers of Egyptian territory to the Nile Delta on the Mediterranean. For millennia this system produced an annual flood, the akhet, driven by the East African monsoon over the Ethiopian highlands, that deposited a renewing layer of nutrient-rich silt across the narrow floodplain, allowing ancient Egyptian agriculture to sustain one of the world's earliest and most durable civilizations without the soil exhaustion that afflicted many other early agrarian societies. Herodotus's often-cited description of Egypt as "the gift of the Nile" (Histories, Book 2) captures this dependence, which archaeologists trace back to the unification of Upper and Lower Egypt under Narmer around 3100 BCE and through the Old, Middle, and New Kingdoms.