The United States and the Soviet Union had been involved in the Cold War for about four decades
Emperor Frederick Barbarossa, King Philip II of France, King Richard I of England
Surplus agricultural production is necessary for development of a civilization. Aside from its annual flood, the Nile was a calm river, easily navigated, at least near its Delta. This made transportation easy, and helped the people of Egypt unite into a single kingdom.
Ships traveling the middle passage carried b. slaves