Danzón: 

Cuban salon dance, originally played by wind bands and subsequently by charangas. Characterized by the cinquillo rhythm of quarter-eighth-quarter-eighth-quarter. The danzón was modernized in the late 30's by Arcano y sus Maravillas, who added a section at the end for harder dancing, called the "mambo" section, which developed into the mambo of the 50's. – Courtesy Afropop Worldwide: www.afropop.org