Salsa music originated in the 1920's. It became very popular towards the 1950's and 1960's.
Salsa music originated in Eastern Cuba. (Around Guantanamo)
Salsa in New York City has a Puerto Rican sound. It has smooth instrumental breaks in many songs.
Salsa in Cuba is typically called 'Timba'. It has a fast tempo. Mostly contemporary styled songs.
Salsa in Columbia is also known as 'Salsa Dura' or 'Hard Salsa'. It has a brass sound. It reminiscent of Cuban Mambo.
Salsa in West Africa expanded, because many slaves traveled from West Africa to Cuba. In the 1940's and 1950's, the Afro-Cuban Salsa rhythm was very popular.