However, the oldest available text on this subject is the "Kama Sutra" ascribed to Vātsyāyana who is often erroneously called "Mallanaga Vātsyāyana". Yashodhara, in his commentary on the "Kama Sutra", attributes the origin of erotic science to Mallanaga, the "prophet of the Asuras", implying that the "Kama Sutra" originated in prehistoric times. The attribution of the name "Mallanaga" to Vātsyāyana is due to the confusion of his role as editor of the "Kama Sutra" with the role of the mythical creator of erotic science. Vātsyāyana's birth date is not accurately known, but he must have lived earlier than the 7th century since he is referred to by Subandhu in his poem Vāsavadattā". On the other hand, Vātsyāyana must have been familiar with the Arthashastra of Kautilya. Vātsyāyana refers to and quotes a number of texts on this subject, which unfortunately have been lost.