Both the "caña" and the "polo" seem to have enjoyed great success and were considered the finest type of flamenco song at the beginning of the 19th century. Serafín Estébanez Calderón, in his book from 1847 "Escenas andaluzas" ("Andalusian Scenes"), mentioned famous singer (the protagonist in one of the scenes), as "King of both polos". He also assured that the "polo" was difficult to sing and that it was derived from the "caña" and mentions the "polo de Tobalo". The polo is widely mentioned in the literature of the 19th century. Most important singers at the time included it in their repertoire, up to the times of Antonio Chacón, who is reported to be one of the latest great performers of this song.