The zarzuela is a form of musical theater from Spain which has the particularity of alternating between dialogues and musical parts. It played an important role in the genesis of tango by introducing the tango andaluz to the city of Buenos Aires.
The first documented mentions of a zarzuela goes back to 1657 with the premier of “El golfo de las sirenas” by Calderon de la Barca. The term zarzuela comes from the name of the royal theater in Madrid where this type of musical play first appeared. In the 19th century a short version of the zarzuela was created, the genero chico, which was more affordable to produce and attend and became popular in Latin american countries including Cuba, Venezuela, Mexico and Argentina.
A zarzuela of the genero chico is a essentially a short comedy composed of one act which lasts for an hour or less. These short plays revolved around popular themes and usually unfold on a single set. They were often inspired by sainetes, another genre of short musical play related to the genero chico .
One of the ways in which the zarzuela influenced on the evolution of tango is by the introduction of the tango andaluz to the city of Buenos Aires. Theaters were an important vehicle through which songs were popularized as people learned and repeated the songs they heard in popular plays. These tangos andaluces soon inspired new local songs which reflected the reality of life in the rapidly growing city of Buenos Aires. Thought these very first tangos criollos did not yet constitute a new distinct musical genre, they are regarded as a very primitive forms of Argentine tango. This is the case for example of “Andate a la Recoleta” (1800), which was inspired by a tango andaluz.
Another way in which the zarzuela played a role in the evolution of tango is through providing a space to present and promote the new local tango as a fully formed and recognized entity. The first documented use of the word “tango” in the sense of tango porteño was found in “Justicia Criolla”, a local zarzuela which proudly features the new tango music, dance and culture.
 Pellettieri, Osvaldo. Historia del teatro Argentino en Buenos Aires. Editorial Galerna, 2002. Print.
 “El dia que el tango tuvo nombre”. Clarín. Online. https://www.clarin.com/espectaculos/dia-tango-nombre_0_S1luFxZRKx.html