The origin of Eisa is unclear, like for many other folk performing arts. Iha Fuyū argued that the name of Eisa was related to "wesa omoro" (), a phrase appearing in Volume 14 of the "Omoro Sōshi" (16th–17th centuries). This theory is no longer supported. It is more likely that the name derived from an exclamation used in the original song of Eisa, the ""Mamauya Ninbuchi"" (). The standardization of the written form was relatively new. Meiji era newspaper articles used various forms including "yensaa" (), "yaisaa" (), and "ensaa" ().