According to Hindu believers, in ancient times, God incarnated in the form of Lord Rama. Rama went into exile with Sita to the forest. Ravana abducted Sita and took her to Lanka. Then Ram went to fetch Sita with the help of Durga Devi and performed ritual of Durga Devi. With blessing and power of Goddess Durga, he defeated ten-headed Ravana and brought Sita back. The festival is observed as commemoration of this event.