Beginning about 5,000 years ago, people in some parts of the world invented writing, in large part to meet the needs of the state. States first developed in the southern part of Mesopotamia known as Sumer, where priests and rulers invented ways to control and organize people who lived in cities reliant on irrigation. Conquerors from the north unified Mesopotamian city-states into larger empires and spread Mesopotamian culture over a large area.

During the third millennium B.C.E. Egypt grew into a cohesive state under a single ruler. For long stretches of history, Egypt was prosperous and secure in the Nile Valley, although at times various groups migrated in or invaded and conquered this kingdom. During the period known as the New Kingdom, warrior-kings created a large Egyptian empire. After the collapse of the New Kingdom, the Nubian rulers of Kush conquered Egypt, and another group, the Phoenicians, came to dominate trade in the Mediterranean, spreading a letter alphabet. Another group, the Hebrews, created a new form of religious belief based on the worship of a single all-powerful god.

In the ninth century B.C.E. the Assyrians used a huge army and sophisticated military tactics to create an empire from a base in northern Mesopotamia. The Persians established an even larger empire, developing effective institutions of government and building roads. The Persians generally allowed their subjects to continue their own customs, traditions, and religions. Around 600 B.C.E. a new religion grew in Persia based on the teachings of the prophet Zoroaster.