>>34181
>What happened to the Vedic religion
From what I understand, Sramana movements started taking over in popularity. For some reason Brahmins lost spiritual authority and various ascetics took over. The whole thing kind of reminds me of the situation in late Roman Empire, with new religions like Christianity, Manichaeism and Mithraism completely overshadowing the old Greco-Roman syncretic religion. At the same time, local non-Aryan populations fused older traditional rituals and mythology with the original Vedic one, often identifying older deities with Indo-Aryan ones, again similar to how syncretism worked in the Roman Empire. The reason for evolution and divergence of practices was urbanization and lack of common political authority.
So, the situation by the establishment of Maurya Empire was this: there were several competing schools, some of which still acknowledged the Vedas (astika) and some that rejected them (nastika) — the Sramana movements. With political unification, the Brahmins started to reconnect the astika traditions, adding new texts that were written during this periods to common practice. Those included Ramayana and Mahabharata, and Bhagavad Gita from Mahabharata became the central work of Hinduism, uniting most of those astika schools. Of course, Hinduism incorporated many beliefs deriving from pre-Vedic Indian religious practices.
Srauta tradition of Hinduism is the closest to the original Vedic religion.
Meanwhile, Sramanic schools developed on their own; out of those Jainism and Buddhism survived as more than just fringe cults.