In plain words
So, whatever worries come, think of Rāma. This was not born today; many thousands of years ago Daśaratha began the thinking of Rāma. To him a daughter was born first, through Kausalyā. She was named ‘Śāntā’. Daśaratha gave her in adoption to his friend Romapāda. Romapāda gave Śāntā in marriage to Ṛṣyaśṛṅga. When Daśaratha performed the Putrakāmeṣṭi rite, Ṛṣyaśṛṅga and Śāntā both came to Ayodhyā.
Before he married Kaikeyī, Daśaratha had promised her father, the king of Kekaya, that he would crown the son to be born to her. “I have two wives, Kausalyā and Sumitrā. But until now no son has been born to me. I need an heir to rule the kingdom. So give me your daughter in marriage,” Daśaratha asked, and then the king of Kekaya: “Daśaratha! Only if you crown the son to be born to my daughter will I give her to you in marriage,” he said. “I will surely do so,” said Daśaratha. Those of the Ikṣvāku line never go back on their word.
Kaikeyī married Daśaratha and came to Ayodhyā. But when no child was born to her either, Daśaratha performed the Putrakāmeṣṭi rite. From that sacred fire a great being appeared and gave him a vessel of pāyasa. Daśaratha shared the pāyasa equally among his three queens. Yet to Kausalyā one son was born, to Kaikeyī one son, but to Sumitrā two sons.