Charvaka
Much of the primary literature of Charvaka, and the Barhaspatya sutras, were lost either due to waning popularity or other unknown reasons. However, there is text that may belong to the Charvaka tradition, written by the skeptic philosopher Jayarāśi Bhaṭṭa, known as the Tattvôpaplava-siṁha, that provides information about this school, albeit unorthodox. Charvaka rejects caste system.