From Trishanku was descended a king named Vahu. Vahu was so addicted to material pursuits that he paid no attention to ruling his kingdom properly. Vahu‘s enemies seized the opportunity to defeat him and deprive him of his kingdom . Vahu and his wife fled to the forest. Chief among these enemies were the Haihayas. But they were aided by the Talajanghas, the Shakas, the Yavanas, the Paradas, the Kambojas and the Pahlavas.
Vahu was old when this happened. Moreover, he was so grief-stricken at having lost his kingdom that he had lost all desire to live. He died in the forest.
King Vahu had two wives. One of these was named Yadavi. The second wife was jealous of Yadavi and attempted to kill her by administering some poison. The poison however did Yadavi no harm. When Vahu died, Yadavi decided to immolate herself on her husband‘s funeral pyre. But the sage Ourva intervened.
―Please do not do that,‖ he requested Yadavi. ―You are expecting and the act of killing the unborn baby would be a crime. Live and let him live. For, he will rule well and will defeat his father‘s enemies.‖
Persuaded by Ourva, Yadavi did not kill herself. She began to live in the sage‘s hermitage. In due course, she gave birth to a beautiful boy. When the baby was born, the poison (gara) also emerged. Since the word sa means together with, the boy was given the name of Sagara.
Ourva took great interest in Sagara‘s upbringing and education. He taught the boy the Vedas and the art of fighting. There was divine weapon known as agneyastra. Sagara also learnt how to use this wonderful weapon from Ourva.
When Sagara grew up, he decided to tackle his father‘s enemies. The knowledge of the divine weapon had made him close to invincible. He defeated the Haihayas, the Shakas, the Yavanas, the Kambojas, the Parada and the Pahlavas. But when he threatened to kill them all, these enemies sought refuge with the sage Vashishtha. The sage asked Sagara to spare them and saved their lives. But they had to be given some sort of punishment. Sagara decreed that the Shakas would have half of their heads shaved off. As for the Yavanas and the Kambojas, their heads were completely shaved off. The Paradas were instructed that they would have to sport long hair and the Pahlavas were forbidden to shave their beards.
King Sagara thus conquered this enemies and became the ruler of the entire world. He decided to perform a horse sacrifice to celebrate his victory.
Sagara had two wives. They were named Keshini and Sumati. Sagara did not have any sons and his wives pleases Ourva with their prayers. Ourva granted them boons that they would have sons. The stipulation however was that one wife would give birth to a single son who would ensure that the line went on. But the other wife would have sixty thousand sons who would perish before having any children of their own.
Keshini desired the single son and accordingly gave birth to Asamanja. Sumati gave birth to a gourd. The gourd was reserved in a vat of clarifed butter. After nine months had passed, sixty thousand sons came out of the gourd.
Sagara‘s sons prospered. When a horse sacrifice is performed, a horse is left free to wander where it wills. At the time when Sagara organized the horse sacrifice, he appointed his sons to look after the horse. These sons insulted the sage Kapila and were burnt into ashes.