India

In India the conquering nomads set up a strict caste system. There were four castes: warrior kings, priests, common people and servants. The powerful priests, or Brahmans, spread the nomad's religion, which became Hinduism. This told the people that their main aim in life was to perform the duties of their caste, and that they may not change caste during their lives.

Around 2500 years ago a new religion called Buddhism emerged from India and spread into China. Indian mathematicians discovered many useful ideas, including the number zero, which is essential for advanced mathematics. But India was largely cut off from Asia by the Himalayas, and so has played little part in world history.