I think I had played this music 25 years ago, when I was living in Mexico. It sounds like a Mexican traditional song, or Mariachi.
I can only remember the phrase written in the score bellow. It's likely that whole music is constructed of similar phrases. I played it with my violin (with few others from violin class), but it is possible that this is usually played by a guitar or trumpet part. I don't know if it has singing on this music.
Key might not be correct.