Brahma told Ravana that the son of Dasharatha and Kausalya would kill him. Once, Dasharatha was traveling through river Sarayu on a boat. His minister Sumantra was also with him. Ravana attacked and destroyed the boat. Dasharatha and Sumantra kept floating towards the sea on a plank from the debris of the boat. In the meantime, Ravana abducted Kausalya and kept her locked in a box on an island. Dasharatha and Sumantra reached that island. There, they found Kausalya locked up inside the box. She was released and gandharva vivaha between Dasharatha and Kausalya took place there.