Vaisvasvata Manu‘s eldest son was Ila. When Vaivasvata Manu became old, he retired to the forest. Ila was appointed the ruler in his place. Ila set out on a voyage of conquest and travelled throughout the world. There was a forest named Sharavana, frequented by Shiva and Parvati. Shiva had decreed that any man who entered the forest would become a woman. King Ila did not know about this rule and set foot in the forest inadvertently he immediaely got transformed into a woman.
―What is going to happen to me now?‖ thought Ila. ―Where will I live?‖ He even forgot all about his earlier life. The moon-god, Chandra, had a son named Budha. While Ila was wandering around. Budha came upon her and fell in love with her. The two had a son named Pururava and Pururava was the ancestor of the lunar line.
Meanwhile, Ikshvaku and the other brothers had started to look for Ila. When they could find no trace of their brother, they asked the sage Vashishtha if he knew of Ila‘s whereabouts. Vashishtha used his mental powers to find out what had happened. He asked the princes to pray to Shiva and Parvati. That was the only way to make Ila a man once more.
The prayers pleased Shiva and Parvati and they found out what the princes wants. ―But what you desire is quite impossible,‖ they told Ikshvaku and his brother. ―Ila can never be made a man once again. At best, we will grant you the following boon. Ila will alternate between being a man
for one month and a woman for one month.‖ The princes had to be content with this. As a woman, Ila continued to be known as Ila. But as a man, he came to known as Sudyumna and had three sons named Utkala, Gaya and Haritashva.