The Purana is a class of literature that treats of ancient religion, philosophy, history, sociology, politics and other subjects. It is an Encyclopaedia of various branches of knowledge and ancient wisdom. It has been defined as a class of literature that contains material on the topics of Creation, Dissolution of Manus, Ages of Manus, Genealogies and the History of glorious kings. For dealing primarily with these subjects it has been called Pancalaksana. A little that was incorporated in the Puranas themselves and had become popular by the Fifth Century A.D., for it was included by Amarasimha in his lexicon 'Amarakosa'.