Why New Religions?
The Later Vedic society was divided into 4 varnas viz. Brahmins, Kshatriya, Vaishyas and Shudras. Birth had become the basis of varnas and two higher varnas viz. Brahmins and Kshatriya were given privileges. The later period saw tensions rising in the varnas. The two dominant varnas Brahmins and Kshatriya competed for dominance. Kshatriya acted as rulers and the reacted against the domination of the priests of Brahmins.
Both Gautam Buddha and Mahavira Jain basically disputed the authority of the Brahmins.
Apart from that India was now developing as a agro based economy. The importance of trade increased and Vaishyas started getting more importance. The Vaishyas came at third position after the Brahmins and Kshatriya and they looked for other religions which could improve their position. The money lending was a trade in post Vedic era, but Brahmins looked down upon this business. The vaishyas wanted some better religious position and that is one of the regions that the trader community “vaishyas” provided support to both Jainism and Buddhism.
There was practice prevalent in the Vedic era that was killing the cattle for sacrifices. This ritual was not accepted in the new agro economy. In fact except Brahmins, almost all common public was irked by the ritualistic practices of the post Vedic period based upon exaggeration, superstition, Brahminical dominance. The position of Shudras got worse to worst.
Sanskrit which was the prime language in the Vedic and post Vedic period now started losing charm. Most people spoke Prakrit. The Position of women got inferior.
Buddhism and Jainism were the movements that started to reform the Hinduism.