There was a king, Mahajanaka, of Mithila in the kingdom of Videha. He had two sons, Aritthajanaka and Polajanaka. When the old king died, the elder brother, Aritthajanaka, became king, and the younger brother his viceroy. In time the new king became suspicious of his brother's popularity with the people and, fearful for his throne, had Polajanaka put in chains. But when Polajanaka proclaimed his innocence, miraculously his chains fell off and he was able to escape to a small village near the frontier of the kingdom. Since he was a strong leader, he attracted many followers.

(Source: www.buddha-images.com/mahajanaka-jataka.asp)