Jainism is a religion of incredible antiquity, stemming from the ascetic Sramana tradition of India, in opposition to the priestly Brahmins and the caste system. The standing principle of Jainism is Ahimsa - non-violence - which is more radically interpreted than in any other religion.
The strict nature of the religion may have played a role in it being relatively little known and not having spread much outside of India. For instance, strictly observant Jains (followers of Jainism) traditionally carry brooms with which to sweep the ground ahead of where they walk, so as to avoid stepping on and killing insects or other small creatures.
Ahimsa has been interpreted differently by different Jain thinkers, with some considering that it dictates total pacifism, while others have stated that defensive violence can be permitted, an interpretation very similar to the Non-Aggression Principle, which states that people should not initiate force or fraud against others.