Mesopotamian civilization: Tigris and Euphrates River Valleys (Southwest Asia)River valleys were the “cradles of civilization.” Early civilizations made major contributions to social, political, and economic development.· Cuneiform: Sumer· Alphabet: Phoenicia· Use of metal (e.g., bronze, iron) tools and weapons· Increasing agricultural surplus: Better tools, plows, irrigation· Increasing trade along rivers and by the sea (Phoenicians)· Development of the world’s first cities· Development of the practice of slavery within most cultures in the ancient world, taking various forms