枢軸時代
Whether in prehistoric or historic times, people always needed to be near reliable sources of drinking water. Settlements developed as early as 4,000 BCE in Iran, in Mesopotamia, in the Indus River valley on the Indian subcontinent, on the banks of Egypt's Nile River, and along China's rivers. As farming developed, grain agriculture became more sophisticated and prompted a division of labour to store food between growing seasons. Labour divisions led to the rise of a leisured upper class and the development of cities, which provided the foundation for civilization. The growing complexity of human societies necessitated systems of accounting and writing. Hinduism developed in the late Bronze Age on the Indian subcontinent. The Axial Age witnessed the introduction of religions such as Buddhism, Taoism, Confucianism, and Jainism.