Onam, or Thiruonam as it is called in Kerala, is a festival to welcome the Asura King Mahabali who visits his subjects once every year. King Mahabali was the ruler of Kerala in the Treta Yuga. He was an Asura, who was extremely fair and benevolent to his subjects. The Devas and other Demi Gods were jealous that an Asura had achieved so much respect and love by the people. They implored upon Lord Vishnu to bring an end to his rule. Vishnu knew that he could not vanquish such a pure soul. He knew of the bountiful nature of Mahabali, who could not deny those who came to him, anything. He decided to take advantage of this trait.
Vishnu took the form of a dwarf Brahmin priest, called Vamana. He approached Mahabali, who agreed to grant him his wish. Vamana asked for land that he could cover in three strides. Mahabali although surprised with this request readily agreed as he assumed it would just be three feet of land. Vamana immediately started growing till he was larger than the whole world. Within two strides he had crossed the earth and the heavens. Now he asked Mahabali where he could place his foot for the third step. Mahabali offered him his head, for he realised it was Vishnu who had come in the guise of the Brahmin priest. Vishnu placed his foot on Mahabali’s head and pushed him down into the Paatalaloka. Before this, Mahabali asked for one boon from Vishnu. He wanted to be able to visit his subjects one day every year. This was granted to him. This is the day that is celebrated as Onam.
