Tantras (from tansu tan, to believe) are the sacred writings of the Hinduls, which are said to have been composed by Siva, and bear the same relation to the votaries of Siva that the Puranas do to the votaries of Vishnu. The Saiva sect look upon the Tantras as the fifth Veda, and attribute to them equal antiquity and superior authority. The observances they prescribe have, indeed, in Bengal, almost superseded the original ritual. The date of the first composition is involved in considerable obscurity; but professor Wilson thinks that the system originated early in the Christian mera, being founded on the previous worship of the female principle and the practices of the Yoga, with the Mantras or mystical formulae of the Vedas. The principal Tantras are the Syamarahasya, Rudrayamala, Mantramahodadhi, Saradatilaka, and Kalikatantra. Rammohun Roy alleges, in his Apology for Vedantic Theism, that among the Tantras there are forged works and passages, published as if genuine, "with the view of introducing new doctrines, new rites, or new precepts of secular law." Some of the Tantras appear to have been written chiefly in Bengal, and in the eastern districts of Hindustan, being unknown in the west and south, and the rites they teach having there failed to set aside the ceremonies of the Vedas, although they are not without an important influence upon the belief and practices of the people. The Saktas (q.v.) derive the principles of their sect, and their religious ceremomies, wholly from the Tantras, and hence are often called Tantraists.