Deepavali is associated with many different things, depending on your beliefs but despite the differences, most of the tales usually have the common theme of good triumphing over evil.
To the South Indians, Deepavali is tied to a myth about Lord Krishna who defeated the cruel demon king, Naraka in a fierce battle. The festival is to commemorate the day the demon was slain, effectively ending his rule of darkness to welcome light into the world.
Up in the North, the story of Deepavali is associated with the Indian epic Ramayana where Lord Rama of Ayuthya
For the North Indians, Deepavali is linked to a myth from the Indian epic, Ramayana. It tells the story of Lord Rama of Ayuthya, who was exiled to the forest for 14 years. After killing the demon Ravana, Krishna returned home with his wife Sita and brother Lakshmana to reclaim his throne. As a gesture, people in the villages lit up their houses with clay lamps – also called diyas – to celebrate the defeat of evil. This tradition continues till today.