Or music theory, mariachi music theory.
I’ll give you some food for thought in the meantime.
From what I gather (and may be subject to debate), the mariachi group has seen three stages of evolution since the French wanted to know the ensemble’s name in the 1800s.
The first stage is Folkloric, usually small groups of string-based players with violins, an harp and various guitars types, with their origins in Michoacan. The skill ceiling is mostly 1 or 2 part singing, fiddler-level violin play, guitar chords and the odd harp solo here and there. Keep in mind that the trumpet use here is anachronistic, since the trumpet was added later on. As example is the old interpretation of El Son de la Negra.
The next stage is Traditional, mostly initiated in Jalisco.
It came with a standardization of uniforms and group elements, instrument experimentation with the addition of trumpets and the integration of classical music theory. That came to be with the involvement of Mariachi music within the golden age of cinema in Mexico in the 40s/50s and preceded with the advent of radio. This is the style that most people remember in general and a backbone to any mariachi’s repertoire, with legendary people which have yet to be replaced, such as Pedro Infante for singers or Miguel Martinez “el Trompas” for the trumpet. As an example of this is an excerpt from the movie Escuela de Vagabundos.
The latest stage is Modern.
As mariachi started to fall in the cultural foreground of Mexico, the musicians started travelling outside of Mexico more often and established themselves further out in America, Europe and Asia. In addition of this expansion, their musical flexibility and the balance within the core elements permits them to be easily inserted into many projects, which often brings them to work with different music genres and even orchestras. As for musicians in this era, we got Vicente Fernandez with a well-aged and very conservative style, Mariachi El Bronx as one of the most progressive approaches and Luis Miguel that uses Pop culture as a middle ground.
Also in regards to progressive Mariachi sound, Mariachi Vargas Introduced songs back in the early 60’s like La Bikina, La Gruta and more Instrumentalized/Personalized songs to give Mariachi a prestigious outlook instead of the negative stereotypes associated with Mariachi. Take in mind this was back in the 60’s and ever since then there was pride that Mariachi could be a Musical style worth musical merit.