The Devi Bhagavata Purana, is one of the eighteen Mahapuranas of Hinduism, composed in Sanskrit by Veda Vyasa. The text is considered as a major purana for Devi worshippers. It promotes bhakti (devotion) towards Mahadevi.
The Devī Māhātmya consists of chapters 81-93 of the Mārkandeya Purana, one of the early Sanskrit Puranas, which is a set of stories being related by the sage Markandeya to Jaimini and his students (who are in the form of birds).
According to Shakta and Vaishnava Puranas, Navaratri falls twice or four times in a year. Of these, the Sharad Navaratri near autumn equinox (September–October) is the most celebrated. In all cases, Navaratri falls in the bright half of the Hindu lunisolar months.