Ayodhya, now in Uttar Pradesh was ruled by a King named Dasharatha centuries ago. He did not have any children. Sage Rishyashringa performed Purtrakameshti for the king. He had three queens and all of them gave birth to 4 children, Rama, Lakshmana, Bharata and Shatrugnan.
After their education in gurukul Sage Viswamitra took Rama and Lakshmana with him. Rama killed demon Tadaka who was disturbing Sage Viswamitras prayers. Sage Viswamitra took Rama and Lakshmana to Kingdom of Janaka. There Rama was married to Sita, Lakshmana married to Urmila. Bharata and Shatrugna was married to Maandavi and Shrutakeerthi who were daughters of younger brother of King Janaka.
Kaikeyi was mother of Bharata. Manthara, her servant convinced her if Bharatha was to be made king Rama had to be sent to forest. Kaikeyi demanded the same with Dasharatha, and he had no option but to sent Rama to forest for 14 years.