Before Ram and his brothers were born, King Dashratha and his first wife Kaushalya had a daughter named Shanta. Kaushalya’s elder sister Vershini and her husband Raja Rompad (who was a great friend of Raja Dashratha as they studied in same Ashram) had no offspring. Once, when Vershini was in Ayodhya, she joked around asking for a child, to which Dashratha promised her she can adopt his daughter, Shanta. As the promise of ‘Raghukul’ had to be kept, Shanta was adopted by Raja Rompad, the king of Angdesh.
One fine day, when Shanta was grown up to be an adult and was now a very beautiful woman, she was in a conversation with Raja Rompad. At this time, a Brahmin came to visit King Rompad requesting help for cultivation during the monsoon. Busy in the conversation with his adopted daughter Shanta, Raja Rompad ignored the Brahmin who left the kingdom. Lord Indra, the God of rains, was offended because a Brahmin devotee of his was insulted. Lord Indra decided to punish Rompad and hence, it did not rain in the coming monsoon.
To get free from this curse, Raja Rompad called a Rishi, Rishi Rishyasringa, to perform a Yagna asking the Lords for rains, which succeeded. To pay honour to the Rishi, King Dashratha and King Rompad decided to marry-off Shanta to Rishyasringa.
As Dahsratha had no heir yet, he then called Rishyasringa to perform a Yagna for him too, after which the God of Fire gave a dessert to Dashratha for his wives to consume, eating which: Ram and his brothers were born.