Of the many texts designated 'Puranas' the most important are the Mahāpurāṇas or the major Puranas. 350 CE, Harivamsa and Vishnu Purana to c. Wendy Doniger, based on her study of indologists, assigns approximate dates to the various Puranas. Gavin Flood connects the rise of the written Purana historically with the rise of devotional cults centering upon a particular deity in the Gupta era: the Puranic corpus is a complex body of materials that advance the views of various competing cults. Pargiter believed the "original Purana" may date to the time of the final redaction of the Vedas. Rajendra Hazra notes that Puranas that survive presently do not follow, partially or totally, the characteristic definition of the scope and contents of Puranas as described in ancient non-Puranic Indian texts.
The extant Puranas, states Coburn, are not identical to the original Puranas. It is important to bear in mind that perhaps a thousand years separates the occurrence of this term in these Upanisads from 'The Puranas' understood as a unified set of texts (see below), and it is therefore by no means certain that the term as it occurs in the Upanisads has any direct relation to what today is identified as 'The Puranas'. The term also appears in the Atharvaveda 11.7.24. Importantly, the most famous form of itihāsapurāṇaṃ is the Mahabharata. The Brhadaranyaka Upanishad refers to Purana as the "fifth Veda", itihāsapurāṇaṃ pañcamaṃ vedānāṃ, reflecting the early religious importance of these facts, which over time have been forgotten and presumably then in purely oral form. They existed in an oral form before being written down, and were incrementally modified well into the 16th century. An early occurrence of the term 'Purana' is found in the Chandogya Upanishad (7.1.2), translated by Patrick Olivelle as "the corpus of histories and ancient tales" (The Early Upanisads, 1998, p. Vyasa, the narrator of the Mahabharata, is hagiographically credited as the compiler of the Puranas. The date of the production of the written texts does not define the date of origin of the Puranas. The Puranic literature wove with the Bhakti movement in India, and both Dvaita and Advaita scholars have commented on the underlying Vedantic themes in the Maha Puranas. The Bhagavata Purana has been among the most celebrated and popular text in the Puranic genre, and is of non-dualistic tenor. The religious practices included in them are considered Vaidika (congruent with Vedic literature), because they do not preach initiation into Tantra. Their role and value as sectarian religious texts and historical texts has been controversial because all Puranas praise many gods and goddesses and "their sectarianism is far less clear cut" than assumed, states Ludo Rocher. The Puranas do not enjoy the authority of a scripture in Hinduism, but are considered a Smriti. They have been influential in the Hindu culture, inspiring major national and regional annual festivals of Hinduism. The first versions of the various Puranas were likely composed between the 3rd- and 10th-century CE. There are 18 Maha Puranas (Great Puranas) and 18 Upa Puranas (Minor Puranas), with over 400,000 verses. The Hindu Puranas are anonymous texts and likely the work of many authors over the centuries in contrast, most Jaina Puranas can be dated and their authors assigned. The content is highly inconsistent across the Puranas, and each Purana has survived in numerous manuscripts which are themselves inconsistent. The Puranic literature is encyclopedic, and it includes diverse topics such as cosmogony, cosmology, genealogies of gods, goddesses, kings, heroes, sages, and demigods, folk tales, pilgrimages, temples, medicine, astronomy, grammar, mineralogy, humor, love stories, as well as theology and philosophy. The Puranas genre of literature is found in both Hinduism and Jainism. Composed primarily in Sanskrit, but also in regional languages, several of these texts are named after major Hindu deities such as Vishnu, Shiva and Devi. The word Puranas (Sanskrit: पुराण, purāṇa) literally means "ancient, old", and it is a vast genre of Indian literature about a wide range of topics, particularly myths, legends and other traditional lore. Maha Puranas Puranas: An introduction and an interpretation, a lecture Puranas: An introduction