The most commonly heralded aspect of the postwar theatre is the collaboration of Richard Rodgers and Oscar Hammerstein II. Both had been major figures in the musical theatre when they first collaborated on Oklahoma!. Given the success of South Pacific, they clone it with another exotic musical about cultural collision based on literary work, The King and I. South Pacific mines another of the new trends of the 1940s, an interest in serious social issues of politics and race. In addition to Rodgers and Hammerstein, the forties also saw the beginning of the other major music-theatre writing team of the forties and fifties. As the musical theatre entered the fifties, there were two clear trends, the developing 'musical play' and the traditional 'musical comedy'. With smaller theatres and less financial pressure, Off-Broadway sought to encourage experimentation. James Rado's and Gerome Ragni's Hair use of rock music brought amplification into the theatre, and its use of nudity attracted much notice.