According to Wikipedia the narcocorrido (drug ballad) “is a subgenre of the Mexican norteño-corrido (northern ballad) music genre, a traditional folk music from northern Mexico, from which several other genres have evolved. This type of music is heard on both sides of the US–Mexican border. Besides from being heard in Mexico, it is widely heard and produced throughout all Latin America. It uses a danceable, accordion-based polka as a rhythmic base. The first corridos that focus on drug smugglers—the narco comes from “narcotics”—have been dated by Juan Ramírez-Pimienta to the 1930s. Early corridos (non-narco) go back as far to the Mexican Revolution of 1910, telling the stories of revolutionary fighters. Music critics have also compared narcocorrido lyrics and style to gangster rap and mafioso rap.
Alt.Latino, an NPR, programme looked at the phenomenon:
They provide the vicarious pleasure of listening to the exploits of poor men made rich in a country where social mobility is difficult, poverty is crippling and government corruption is rampant. In that way, they might not be that different from telenovelas: escapist entertainment that’s not always wholesome, and that can celebrate toxic behaviour.
Here are a couple of examples: