In some cultures, exposure of the midriff is socially discouraged or even banned, and the Western culture has historically been hesitant in the use of midriff-baring styles. Bill Blass commented, "It is too difficult. Women will much more readily wear bare-back or plunging-neckline styles." It was introduced to fashion in 1932 by Madeleine Vionnet when she offered an evening gown with strategically cut openings at the waist. Women's swimwear of the 1930s and 1940s incorporated increasing degrees of midriff exposure. Teen magazines of late 1940s and 1950s featured similar designs of midriff-baring suits and tops. However, midriff fashion was stated as only for beaches and informal events and considered indecent to be worn in public. However, exposure of the female midriff and navel was widely brought into everyday Western women's fashion in the 1960s' sexual revolution and later with the popularity of halters, tube tops and crop tops in the 1970s. The cheerleading style fashions developing largely from the styles originating with the Dallas Cowboys Cheerleaders in the early 1970s also played a crucial role for the popularity of midriff fashion at middle and high schools.