How did King Polybus die?

King Polybus of Corinth died of natural causes, specifically old age, as depicted in Sophocles' play "Oedipus Rex." His death was not caused by any external events or actions but was a result of the natural course of life. This event is significant because it highlights the themes of fate and the consequences of Oedipus's actions, as he believed he had escaped the prophecy regarding his parents.