in the caste system which group of people fit into the Upper Class society

In the caste system, the group of people which fit into the Upper Class society were the Brahmins. The Brahmins were a caste of people who had attained the highest spiritual knowledge. This included priests and religious teachers. Unlike some other religions and since this was part of a caste system, people could not just become important religious leaders, rather it was passed on through inheritance. In some circumstances, Brahmins could be warriors.

heres an image of the caste system