Vijayadashami is celebrated on the tenth day of the Hindu autumn lunar month of Ashvin, or Ashooja which falls in September or October of the Western calendar, from the Shukla Paksha Pratipada, or the day after the new moon which falls in Bhadrapada, to the Dashami, or the tenth day of Ashvin. It is the culmination of the 10-day annual Navaratri festival.

On this day in the Treta Yug, lord Rama, the seventh incarnation of Vishnu, killed the great demon Ravana who had abducted Rama’s wife Sita to his kingdom of Lanka. Rama, his brother Lakshman, their follower Hanuman and an army of monkeys fought a great battle to rescue Sita.

Rama had performed “Chandi Homa” and invoked the blessings of Durga, who blessed Rama with secret knowledge of the way to kill Ravana. On the day of Ashvin Shukla Dashami, Rama’s party found Sita and defeated Ravana. Based on the inferences from Balmik’s Ramayana, Kalidas’s Raghuvans, Tulsidas’s Ram Charit manas, and Keshavdas’s Ram Chandra Yas Chandrika as well as common perception of Hindus, Ram, Sita, and Lakshman returned to Ayodhya on the 30th day of Ashvin (19–20 days after Vijay Dashmi). To mark the return of Lord Ram, in the evening, the residents of Ayodhya lighted their city with millions of earthen lamps (called Deepak). Since then, this day is celebrated in India as Deepawali or Diwali.

During the ten days of Dasha-Hara, effigies of Ravana, his brother Kumbhakarna and son Meghanad are erected and burnt by enthusiastic youths at sunset.