Sri Mapanji Jayabaya (or Jayabhaya) reigned over the kingdom of Kediri in East Java from 1135 to 1157 AD. He reunified Java after a split that occurred with the death of his predecessor Airlangga . He is also remembered for his just and prosperous rule, and reputed to have been an incarnation of the Hindu deity Vishnu. He is the archetypal 'just king' (ratu adil) who is reborn during the dark age of reversal (jaman edan) at the end of each cosmic cycle to restore social justice, order, and harmony in the world.

His name is mentioned in the manggala (prologue) of the famous kakawin (Old Javanese poetry in Indian meteres) Bharatayuddha as the patron of the two poets; mpu Sedah and mpu Panuluh who wrote this work.

When Japan took Java, in the first weeks of 1942, Indonesians danced in the streets, welcoming the Japanese army as the fulfillment of a prophecy made by King Jayabaya, who foretold the day when white men would one day establish their rule on Java and tyrannize the people for many years – but they would be driven out by the arrival of yellow men from the north. These yellow men, Jayabaya predicted, would remain for one crop cycle, and after that Java would be freed from foreign domination. To most of the Javanese, Japan was a liberator: the prophecy had been fulfilled. The Japanese not only freed Indonesian nationalists from Dutch dungeons, but hired them on as civil servants and administrators. In the waning days of 1944, however, it was clear that Japan could not win the war. The Japanese officially granted Indonesia its independence on August 9, 1945, and the commander of Japan's southeast Asian forces appointed future President Sukarno as chairman of the preparatory committee for Indonesian independence. As one account of Indonesian history puts it, "With the minor exception that three crops had been harvested, Jayabaya's prophecy had been realized."

Together with the prophecy of Sabdapalon to return, after 500 years and at a time of widespread political corruption and natural disasters (in 1978), to sweep Islam from the island and restore Hindu-Javanese religion and civilization, Jayabaya's prophecy has given much heart to the Indonesian Hindu communities.

Many believe that the time for the arrival of a new ratu adil is near (as the prophesies put it, "when iron wagons drive without horses and ships sail through the sky [i.e. cars and airplanes]"), and that he will come to rescue and reunite Indonesia after an acute crisis, ushering in the dawn of a new golden age.