Festival · Shakta · Pan-India
Navaratri
The nine nights of the Goddess in the bright half of Ashvin that lead up to Vijayadashami. The Devi Bhagavata has Narada teach the vow to Rama; in Bengal the same days are Durga Puja.
Sources: The Srimad Devi Bhagavatam, tr. Swami Vijnanananda (1921-22), book 3, chapter 30: Rama's Navaratri vow; Durga Puja, Wikipedia · see Navaratri's web