After Cortes’ invasion and conquest, Mexico became a Spanish colony and remained under Spanish dominion for the next two hundred years, incorporating their Pre-Columbian roots together with the lasting influence that came with the Spanish. Both folk and classical music have drawn from these, and regional styles reflect these traditions. The Spanish regime also imported African slaves, adding a third dimension to the areas music.
Mexican son first appeared in the 17th century and is a fusion of indigenous, Spanish and African traditions, much like Cuban son. But in Mexico, the music exhibited lots of variation from region to region, both in rhythm and instrumentation. Some of these regional sones include son jarocho from the area around Vera Cruz, son jaliscenses from Jalisco, son huasteco, son calentano, son michoacano, etc.
Ranchera is an outgrowth of son jalescenses. A type of song that was literally sung on a Mexican ranch, ranchera originated in the mid-19th century, just before the Mexican revolution. The music concerned itself with traditional themes of love, patriotism and nature. Ranchera songs are not just one rhythm; the music is basically a waltz, polka or bolero. Their form is standardized with an instrumental introduction and conclusion, with verse and refrain in the middle.
We tend to think of Mariachi as a style of music, but its actually a group of musicians. There is some disagreement about where the name 'Mariachi' comes from. Some music historians believe that it is derived from the french "mariage" (marriage) and indeed, such groups formed and still form an essential part of weddings in Mexico. An alternate theory posits that the word comes from a Coca Indian word that originally referred to the platform on which the orchestra performed.
Evolution of Mariachi :
There is no one type of music that mariachis play, although they are closely tied to ranchera music. Originally mariachi and ranchera were mostly about romantic themes, but as the Mexican economy worsened, the haciendas could no longer afford to have their own mariachi band on the premises and they let the musicians go. As a result of unemployment and harder times, the mariachi began to change themes, singing about revolutionary heroes or current events.
By the early 20th century, mariachi previously known only through their various regional styes began to coalesce into a uniform musical genre, one that became recognizable throughout all of Mexico. That was due, in large part, to musicians Silvestre Vargas and Ruben Fuentes of the mariachi group "Vargas de Tecalitlan" who made sure that the popular music was written down and standardized.