The nāstika schools are (in chronological order):
Each school of Hindu philosophy has extensive epistemological literature called Pramana-sastras.
In Hindu history, the distinction of the six orthodox schools was current in the Gupta period "golden age" of Hinduism. With the disappearance of Vaisheshika and Mīmāṃsā, it became obsolete by the later Middle Ages, when the various sub-schools of Vedanta (Dvaita "dualism", Advaita Vedanta "non-dualism" and others) began to rise to prominence as the main divisions of religious philosophy. Nyaya survived into the 17th century as Navya Nyaya "Neo-Nyaya", while Samkhya gradually lost its status as an independent school, its tenets absorbed into Yoga and Vedanta.