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, a new structure of governance in which leaders gained and maintained power through organized violence, bureaucracies, systems of taxation, social and gender hierarchies, and often written laws. 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 in the Nile River Valley that provided rich farmland and an avenue of communication. For long stretches of history, Egypt was prosperous and secure in the Nile Valley, although at times various groups migrated into or invaded and conquered this kingdom. During the period known as the New Kingdom, warrior-kings created a large Egyptian empire. Newcomers and Egyptians often adopted aspects of each other’s cultures. 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. The Hebrews wrote down their religious laws and traditions in a series of books, which became the core of the Hebrews’ religion, Judaism.

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, who emphasized the individual’s responsibility to choose between good and evil.