(c. 1100 – c. 500 BCE), predating the Buddha and the Mahavira. Though no direct evidence of this has been found, the tribes of the Ganges valley or the Dravidian traditions of South India have been proposed as another early source of reincarnation beliefs. The idea of reincarnation, Saṁsāra, did not exist in the early Vedic religions. The early Vedas do not mention the doctrine of Karma and rebirth but mention the belief in an afterlife. It is in the early Upanishads, which are pre-Buddha and pre-Mahavira, where these ideas are developed and described in a general way. Detailed descriptions first appear around the mid-1st millennium BCE in diverse traditions, including Buddhism, Jainism and various schools of Hindu philosophy, each of which gave unique expression to the general principle. The texts of ancient Jainism that have survived into the modern era are post-Mahavira, likely from the last centuries of the first millennium BCE, and extensively mention rebirth and karma doctrines. The Jaina philosophy assumes that the soul (jiva in Jainism; atman in Hinduism) exists and is eternal, passing through cycles of transmigration and rebirth. After death, reincarnation into a new body is asserted to be instantaneous in early Jaina texts. Depending upon the accumulated karma, rebirth occurs into a higher or lower bodily form, either in heaven or hell or earthly realm. No bodily form is permanent: everyone dies and reincarnates further. Liberation (kevalya) from reincarnation is possible, however, through removing and ending karmic accumulations to one's soul. From the early stages of Jainism on, a human being was considered the highest mortal being, with the potential to achieve liberation, particularly through asceticism. The early Buddhist texts discuss rebirth as part of the doctrine of Saṃsāra. This asserts that the nature of existence is a "suffering-laden cycle of life, death, and rebirth, without beginning or end." Also referred to as the wheel of existence (Bhavacakra), it is often mentioned in Buddhist texts with the term punarbhava (rebirth, re-becoming). Liberation from this cycle of existence, Nirvana, is the foundation and the most important purpose of Buddhism. Buddhist texts also assert that an enlightened person knows his previous births, a knowledge achieved through high levels of meditative concentration. Tibetan Buddhism discusses death, bardo (an intermediate state), and rebirth in texts such as the Tibetan Book of the Dead. While Nirvana is taught as the ultimate goal in the Theravadin Buddhism, and is