The grandaughter of famed traditional singer, 'Toto La Momposina', explains the origins of the Cumbia and its importance in Colombia's historical social fabric.
http://www.youtube.com/watch?v=-l5yTrmo4eU

Cumbia is a Latin American music style that originated in Colombia's Caribbean coastal region. Traditional cumbia and its associated dance is considered to be representative of Colombia, along with Vallenato, Bambuco and Pasillo. Cumbia originated in the Caribbean coast of eastern Colombia, but there are also folkloric variants in Panama. During the mid-20th century, Colombian band leaders such as Pacho Galan and Lucho Bermudez orchestrated this Caribbean folklore and brought it to different parts of Latin America, where it gained particular popularity in Mexico, Argentina, and the Andean region. Cumbia began as a courtship dance practiced among the African slave population that was later mixed with European instruments and musical characteristics. Cumbia is very popular in the Andean region and the Southern Cone and was until the early 1980s more popular in these regions than the salsa.^[1]
http://www.last.fm/music/Aniceto+Molina/_/Cumbia+Colombiana