Buddhism began in northeast India in the 5th century B.C. It was founded by Siddhartha Gautama, a clan prince who saw suffering in the world and set out on a quest to find a cure. After reaching enlightenment, he began teaching those around him the Four Noble Truths of Buddhism.
In the third century B.C., the Indian emperor Asoka adopted Buddhism and sent out missionaries throughout Asia. Shortly afterward, Buddhism began to decline in India, but it took root in Sri Lanka, where it became the national religion. From there, it spread throughout eastern Asia, notably influencing Tibet, China, Korea and Japan.