On this day in the Treta Yug, Rama, also called Shri Ram, the seventh avatar of Vishnu, killed the great demon Ravana who had abducted Rama's wife Sita to his kingdom of Lanka. Rama, his brother Lakshmana, their follower Hanuman and an army of monkeys fought a great battle to rescue Sita. The entire narrative is recorded in the epic Ramayana, a Hindu scripture.
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. Thus it is termed as Vijaya Dashami. Based on the inferences from Valmiki’s Ramayana, Kalidas’s Raghuvans, Tulsidas’s Ram Charit Manas, and Keshavdas's Ram Chandra Yas Chandrika as well as common perception in India, Rama, Sita, and of Lakshmana returned to Ayodhya on the 30th day of Ashvin (19–20 days after Vijayadashmi). To mark the return of Lord Rama, in the evening, the residents of Ayodhya lit their city with millions of earthen lamps (called Deepak). Since then, this day is celebrated in India as Deepawali or Diwali.