In the fifth and sixth century B.C. the leading position of the Brahmin priests was criticised by the Kshatriya caste
They priests had become dominant, were arrogant and oppressed the other castes. The many rituals and offerings lead to exploitation of the poor. The Brahmin priests used the god to extend the illness and by doing so they earned more money.
The most important man who stood up against this system was Vardamana and Siddhartha Gautama. Both rejected the system and searched for Enlightenment.
Siddhartha Gautama, later Bhudda :
Siddhartha Gautama was born in 566 B.C. He was the son of a king of the Shakya-clan in present Nepal. He got married with princess Yasodra when he was 16 and he had one son. On the few occasions that he came out of the royal residence, he saw an ill man, a dead man and an old man. He was disturbed by seeing it. This could also happen to him. He was troubled by how to escape from this. He had to follow 4 stadia of increasing understanding (jhanas) to achieve Enlightenment. See Buddha incarnation 9 of Vishnu.