Musical theater is a special category of drama with its own unique elements. Throughout theater history, drama has been closely associated with music and dance. Whether in the form of the dramas of ancient Greece, or in opera, operetta, vaudeville and burlesque, the fusion of theater, music, and dance has been extremely popular. The modern musical comedy, as developed in the United States, has become recognized worldwide as a unique and exciting form of theater. With its roots in vaudeville, burlesque, and the minstrel show, by the early 1900s the American musical theater had begun to emerge in the works of George M. Cohan. Cohan made his dialogue more realistic and down-to-earth than was common for musicals of the time, and he moved his shows more toward the book musical. By the 1920s and 1930s, composers such as Irving Berlin, Jerome Kern, George Gershwin, Cole Porter, and Richard Rodgers were bringing fresh and innovative work to the American musical stage. The 1927 production of Show Boat offered an advance over previous musicals. In 1931, Of Thee I Sing was the first musical to receive the Pulitzer Prize. While the 1943 production of Oklahoma! is sometimes hailed as being more revolutionary than it really was, it can be praised for integrating the songs with the story and creating several dances that advanced the story. The 1940s and 1950s are seen by many to be the golden age of musicals. Musicals such as South Pacific, Guys and Dolls, and My Fair Lady stand out as remarkable contributions to the world of theater. The 1960s through the 1990s saw the rise of the concept musical, which was built around an idea rather than a story. The works of Stephen Sondheim are examples of such musicals. In addition, these years saw the ascendancy of dancers and choreographers, as well as the entry of British composers and lyricists onto the Broadway musical stage. However, American performers and directors are still the premier interpreters of the form.