River Nile
The Eastern Sahara has very high temperatures (average: Cairo 21 °C, Luxor 24 °C) and almost no rainfall. Agriculture was possible only through irrigation using Nile water, which is why the Greek historian Herodotus called Egypt “the gift of the Nile.”
Upper Egypt consisted of a 650 km-long narrow Nile valley; Lower Egypt formed a fan-shaped delta up to 200 km wide at the coast.
The White Nile (from East Africa’s Lake Victoria region) and the Blue Nile (from the Ethiopian highlands) merge in Sudan. Seasonal monsoon rains in Ethiopia caused the annual flooding of the Nile from June to August, depositing 1–3 m of fertile black silt along the valley — the natural fertilizer of Egypt.
Irrigation and Political Organization
The need to organize irrigation and water storage efficiently led to the formation of regional centers of power along the Nile. Conflicts among these local rulers, combined with raids by nomads, encouraged a concentration of authority, ultimately resulting in Egypt’s unification.
To regulate the water supply, Egyptians developed basin irrigation around 3500 B.C. — an early hydraulic system that stored floodwater for use during the dry season. This allowed the expansion of farmland and higher yields, but also increased dependence on centralized administration.
As cooperation grew, larger regional units formed under local princes (nomarchs), who governed from central towns. They organized defense, collected tribute, and managed irrigation.
Over time, rivalry among these nomarchs led to conflicts, which ended around 3100 B.C. with the unification of Upper and Lower Egypt under kings from the south.
- Basin irrigation: Parts of the Nile flood were stored in artificial basins for later use in the dry season.
- Nomads: Non-sedentary herders of the savannas, steppes, and deserts; increasing desertification often pushed them into the fertile Nile valley.