Originally the Emperor and non-warrior nobility employed these warrior nobles. In time, they amassed enough manpower, resources and political backing in the form of alliances with one another, to establish the first samurai-dominated government. As the power of these regional clans grew, their chief was typically a distant relative of the Emperor and a lesser member of either the Fujiwara, Minamoto, or Taira clans. Though originally sent to provincial areas for a fixed four-year term as a magistrate, the toryo declined to return to the capital when their terms ended, and their sons inherited their positions and continued to lead the clans in putting down rebellions throughout Japan during the middle- and later-Heian period. Because of their rising military and economic power, the warriors ultimately became a new force in the politics of the court. Their involvement in the Hōgen in the late Heian period consolidated their power, and finally pitted the rival Minamoto and Taira clans against each other in the Heiji Rebellion of 1160.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): Who fought in the Heiji Rebellion?
the rival Minamoto and Taira clans