Trilogies (Greek: τριλογία trilogia)[3][4] date back to ancient times. In the Dionysia festivals of ancient Greece, for example, trilogies of plays were performed followed by a fourth satyr play. The Oresteia is the only surviving trilogy of these ancient Greek plays, originally performed at the festival in Athens in 458 BC. The three Theban plays, or Oedipus cycle, by Sophocles, originating in 5th century BC, is not a true example of a trilogy because the plays were written at separate times and with different themes/purposes.