Part of Hinduism. Introduced 600 BCE.
Vedanta (meaning 'End of the Vedas') is the formalization of the Hindu philosophy first expressed in the Vedic Upanisads (written between 600 and 400 BCE). These texts introduced the concepts of Karma ('whatever action he does, that he attains') and Samsara.
Samsara is the cycle of rebirth, wherein one remains trapped in the cycle of rebirth into successive earthly forms until one realizes the ultimate truth - that there is no distinction between Self (Atman) and the Absolute (Brahma), and which point one's soul is united with Brahma, the Absolute.
'Vedanta', 'Samsara' and 'Karma' in The Oxford Dictionary of World Religions, ed. by John Bowker (Oxford: Oxford University Press, 1997).