European discovery in the History of the Galapagos Islands occurred when Dominican Fray Tomás de Berlanga, the fourth Bishop of Panama, sailed to Peru to settle a dispute between Francisco Pizarro and his lieutenants. De Berlanga's vessel drifted off course when the winds diminished, and his party reached the islands on 10 March 1535. According to a 1956 study by Thor Heyerdahl and Arne Skjølsvold, remains of potsherds and other artifacts from several sites on the islands suggest visitation by South American peoples prior to the arrival of the Spanish.