Analysis of information sources in references of the Wikipedia article "Historical Vedic religion" in English language version.
... in certain other places [of Rigveda], an approach is being made to the idea of Transmigration. ... There we definitely know that the whole hymn is address to a departed spirit, and the poet [of the Rigvedic hymn] says that he is going to recall the departed soul in order that it may return again and live.
This [the primitive religion of the Vedas] resulted, after a period of confusion, in the formation of a new system, Brahmanism (or Hinduism), which is essentially a philosophy, a metaphysic, a work of human speculation, ...; [footnote 1]... the neuter, Brahman, as the one impersonal substance.
The early Upanishads are primarily metaphysical treatises concerned with identifying the Brahman, the ground of the universe. ... The essence of early Brahmanism is the search for the Absolute and its natural development is in Vedantin monism which claims that the soul is identical with the Absolute.
It [Vedic religion] takes its name from the collections of sacred texts known as the Vedas. Vedism is the oldest stratum of religious activity in India for which there exist written materials. It was one of the major traditions that shaped Hinduism.
About half of the Kalash practice a form of ancient Hinduism infused with old pagan and animist beliefs.