Historically, the roots of Buddhism lie in the religious thought of ancient India during the second half of the first millennium BCE. That was a period of social and religious turmoil, as there was significant discontent with the sacrifices and rituals of Vedic Brahmanism.
It was challenged by numerous new ascetic religious and philosophical groups and teachings that broke with the Brahmanic tradition and rejected the authority of the Vedas and the Brahmans. These groups, whose members were known as shramanas, were a continuation of a non-Vedic strand of Indian thought distinct from Indo-Aryan Brahmanism.
Scholars have reasons to believe that ideas such as samsara, karma (in the sense of the influence of morality on rebirth), and moksha originated in the shramanas, and were later adopted by Brahminorthodoxy.
This view is supported by a study of the region in which these notions originated. Buddhism arose in Greater Magadha, which stretched from Sravasti, the capital of Kosala in the north-west, to Rajagrha in the south east. This land, to the east of aryavarta, the land of the Aryas, was recognised as non-Vedic.
Other Vedic texts reveal a dislike of the people of Magadha, in all probability because the Magadhas at this time were not Brahmanised. It was not until the 2nd or 3rd centuries BCE that the eastward spread of Brahmanism into Greater Magadha became significant. Ideas that developed in Greater Magadha prior to this were not subject to Vedic influence. These include rebirth and karmic retribution which can be found in a number of movements in Greater Magadha, including Buddhism. These movements inherited notions of rebirth and karmic retribution from an earlier culture
At the same time, these movements were influenced by, and in some respects continued, philosophical thought within the Vedic tradition as reflected e.g. in theUpanishads. These movements included, besides Buddhism, various skeptics (such as Sanjaya Belatthiputta), atomists(such as Pakudha Kaccayana), materialists (such as Ajita Kesakambali), antinomians (such as Purana Kassapa); the most important ones in the 5th century BCE were the Ajivikas, who emphasized the rule of fate, the Lokayata (materialists), theAjnanas (agnostics) and the Jains, who stressed that the soul must be freed from matter.
Rock-cut Lord –Buddha– Statue at Bojjanakonda near Anakapalle ofVisakhapatnam dist in Andhra Pradesh
Many of these new movements shared the same conceptual vocabulary - atman (“Self”), buddha (“awakened one”), dhamma(“rule” or “law”), karma (“action”), nirvana (“extinguishing”), samsara (“eternal recurrence”) and yoga (“spiritual practice”).
The shramanas rejected the Veda, and the authority of the brahmans, who claimed to be in possession of revealed truths not knowable by any ordinary human means; moreover, they declared that the entire Brahmanical system was fraudulent: a conspiracy of the brahmans to enrich themselves by charging exorbitant fees for the performance of bogus rites and the giving of futile advice.
A particular criticism of the Buddha’s was Vedic animal sacrifice.
The Buddha declared that priests reciting the Vedas were like the blind leading the blind. According to him, those priests who had memorized the Vedas really knew nothing. He also mocked the Vedic “hymn of the cosmic man”.
He declared that the primary goal of Upanishadic thought, the Atman, was in fact non-existent, and, having explained that Brahminical attempts to achieve liberation at death were futile, proposed his new idea of liberation in life.
At the same time, the traditional Brahminical religion itself gradually underwent profound changes, transforming it into what is recognized as early Hinduism. In particular, the brahmans thus developed “philosophical systems of their own, meeting the new ideas with adaptations of their doctrines”.