King Arithajanaka was the father of Mahajanaka who was killed by Polajanaka, his younger brother in the war of succession in the Mithila Kingdom. His mother, the wife of King Arithajanaka escaped to the city of Jumpa and stayed with the Brahmin Tisapamok who acted as her eldest brother until she gave birth to Mahajanaka. Mahajanaka studied the liberal arts until he finished at the age of 16. He thought about getting the throne back from his umcle.

He asked for the property belonging to his mother to do business. When the opportunity arose to get the throne back, Mahajanaka together with two traders from Suwanaphum hired a boat to sail to Suwanaphum. During their journey a storm sank their boat. Mahajanaka did not lose his mind and floated for 7 days. On a full moon day, even though he was being tossed about by the waves, he undertook to follow the 8 Precepts. Nangmaneemekhia, an angel protector of the ocean, came to see him and put him through various trials. The result of Mahajanaka's fortitude was that Nangmaneemekhia was convinced to take him back to Mithila, according to his wish.

In the meantime King Polajanaka of Mithila passed away without an heir, except for his daughter named Siwalee who had a very sharp mind. Purohit, a high-ranking official, took it upon himself to use the King's horse carriage to Mahajanaka who was sleeping in a garden. Purohit looked and had the impression that he could be the King, so he invited him to ascend the throne. Mahajanaka accepted the invitation and performed the coronation ceremony in Mithila. Princess Siwalee tested his wisdom in different ways to see if Mahajanaka had the adility to govern as Pholajanaka would have wished. He then decided to marry Princess Siwalee and he ruled over Mithila with benevolence.