The document discusses early river valley civilizations including the Sumerians in Mesopotamia, the ancient Egyptians along the Nile River, the Indus Valley civilization in India, and early Chinese civilization along the Yellow River. Key developments discussed include the Sumerians creating the first known writing system of cuneiform, tightly organized city-states in Mesopotamia and Egypt ruled by divine kings, and advances in agriculture, trade, architecture, mathematics and astronomy in these early civilizations. The legacies of these river valley peoples included innovations like the wheel, early systems of writing, and influences on art, architecture and divisions of time.