Once, emperor Sagar performed an Ashwamedha Yagya. Indra abducted the horse used in this Yagya and kept it in the hermitage of Sage Kapila. All the sixty thousand sons of Sagar went to search the horse and found it in Kapila’s hermitage.
Hearing the commotion and noise, sage Kapila who was engrossed in his meditation opened his eyes and came out to see what was happening. He was very angry. He looked angrily towards the sons of Sagar. All of them were burnt to death except four.
In due course of time, Sage Bhagirath became successful in bringing river Ganga to earth with the blessings of lord Shiva. Bhagirath was the descendants of Sagar. Bhagirath made all of his ancestors alive who had met an untimely death by sprinkling the water of Ganga on their bones. River Ganga is also known as Bhagirathi because of Bhagirath.