Long long ago there lived in Lanka three rakshasas named Ravana, Kumbhakarna and Vibhishana, all sons of Visravas.
Through hard penance the three brothers obtained valuable boons from Brahma, the Creator.
Ravana was assured that he would be free from death except at the hands of men. Kumbhakarna, because of a slip of his tongue, was blessed with long spells of undisturbed sleep. Vibhishana asked for and got the boon that his devotion to Mahavishnu, the Protector, would never diminish.
Assured of his might, Ravana defeated Kubera, the God of wealth, in a great battle. Ravana seized from Kubera the island of Lanka and a Pushpaka Vimana in which, by a mere wish, he could travel anywhere he liked.
When Ravana became the ruler of Lanka, all the rakshasas living beneath the earth came over to the island. The rakshasas were very cruel. They fought against the Devas and tormented the rishis. Unable to bear the harsh rule of Ravana, the Devas complained to Brahma.
Brahma, accompanied by the Devas, waited on Lord Vishnu and prayed that both heaven and earth be saved from the evil of the rakshasas.
Sriman Narayana, which is another name for Vishnu, asked the Devas to take courage and shed their fears. He assured them he would appear on earth as a mortal and deal with Ravana and his followers.
He announced that He would take the form of the four sons of Dasaratha, Emperor of Ayodhya. He asked the Devas to assume the shape of vanaras and help the Protector.
Now Dasaratha of the Surya (Sun) dynasty had reigned over Ayodhya, a prosperous kingdom in the valley of the Ganga, for sixty thousand years. Yet he had no children by any one of his three wives.
He decided to perform the great sacrifice known as Putrakameshti for obtaining from the Gods the gift of parenthood. He was anxious to beget a child who would become the heir to the throne and continue the dynasty.
At the end of the sacrifice which he performed with the help of sages and wise men a Deva Duta (heavenly messenger) appeared from the fire and handed to Dasaratha a bowl of sacred Payasam (porridge) to be given to the three queens so that they might beget children.