Traditionally performed by poor workers of African descent in streets and "solares" (courtyards), rumba remains one of Cuba's most characteristic forms of music and dance. Vocal improvisation, elaborate dancing and polyrhythmic drumming are the key components of all rumba styles. "Cajones" (wooden boxes) were used as drums until the early 20th century, when they were replaced by "tumbadoras" (conga drums). During the genre's recorded history, which began in the 1940s, there have been numerous successful rumba bands such as Los Papines, Los Muñequitos de Matanzas, Clave y Guaguancó, AfroCuba de Matanzas and Yoruba Andabo.