En route to Mithilā, while passing through a lush forest, Vishwāmitra recounted the story of his ancestors to Rāma and Lakshmana.
Many years ago, there lived a virtuous king called Kush, who was the son of Lord Brahma himself. He was married to the princess of Vidarbha, who bore him four mighty sons, namely- Kushāmbh, Kushnābh, Astoorjas and Vasu. As advised by their father, the four brothers established their own kingdoms and began ruling them. Kushāmbh established Kaushambhi, Kushnābh established Mahoday, Astoorjas established Dharmāranya, while Vasu set up the city of Girivraj.
Through Apsarā Ghritachi, King Kushnābh had a hundred daughters. All the daughters grew up to be abundantly pretty and graceful. One day, all the hundred of them began to sing and dance merrily in the royal courtyard, when Vāyu deva appeared in front of them. A bewitched Vāyu deva confessed his love for all of them and proposed marriage to them. However, the princesses laughed the proposal off. They firmly asserted that they would never marry anyone by their own will and that they shall marry only the one their father confers them upon.
Vāyu deva became furious at this rejection and hence disfigured their body, leaving them hunchbacked. All of them were horrified at their haggard appearance. In a bashful state, they ran towards their father Kushnābh and told him everything that had transpired at the courtyard.
Kushnābh consoled his daughters and commended their steadfastness with their Dharma, family honour and forgiveness.
Time passed and Kushnābh started to ponder over the marriage of his daughters. At that time, there was a king called Brahmadutta, born out of the union of a Rishi and Gandharva woman, who ruled the city of Kāmpilya. Kushnābh offered his daughter's hand to Brahamdutta. The moment Brahmadutta held the hand of those princesses, their curse was uplifted and they assumed their former, unblemished form back.
After getting the daughters of Kushnābh in marriage, Brahamdutta left for his abode. Now it was time for Kushnābh to think about a son. In order to beget a son, he conducted a Putrakāmesthi yajna. As a result, he was blessed with a son called Gādhi. In hindsight, Gādhi had two children of his own — a daughter called Satyavati and a son called Kaushika, who would eventually become the future Bramharishi Vishwāmitra.
Jai Shree Ram! 🙏🕉️
Source: Sarg 32–34, Bāla Kānd, Vālmiki Rāmāyana