The Curse of Sagar's Sons

With the two princes and his students, Vishwamitra left his Siddhashram and set out for Mithila. When they approached the Ganga River, Vishwamitra began narrating a story about the river, one that concerned the kings of the Solar Dynasty. Ganga was the eldest daughter of Himavan, and her younger sister, Uma, was Lord Shiv's wife. Sagar, a king of the Solar Dynasty, had two wives: Keshini and Sumati. Keshini had an intellectually disabled son named Asamanjas, while Sumati had sixty thousand sons. Everyone loved Asamanjas’s son, Amshuman.

Once, when King Sagar was planning an Ashvamedh Yagya, Indra rode away with the yagya's horse. Sagar sent his sixty thousand sons to search for and retrieve the horse. In their eagerness to find it, they caused a commotion that disturbed Maharshi Kapil’s meditation. Angered, Kapil cursed Sagar and Sumati’s sixty thousand sons to be burned to ashes. Garud, the king of birds and Sumati’s brother, found the horse, returned it to Amshuman, and advised him to complete the yagya. After that, Amshuman was to bring Ganga to earth and free his ancestors from the curse.