This had its origin with the African Negro slaves imported into Cuba, whose dances emphasized the movements of the body rather than the feet. The tune was considered less important than the complex cross rhythms, being provided by a percussion of pots, spoons, bottles, etc. (Raffe, 1964, 431).
It evolved in Havanna in the 19th century by combination with the Contradanza (Sadie, 1980, 5/86). The name 'Rumba' possibly derives from the term 'rumboso orquestra' which was used for a dance band in 1807 (Sadie, 1980, 5/88), although in Spanish, the word 'rumbo' means 'route', 'rumba' means 'heap pile', and 'rhum' is of course an intoxicating liquor popular in the Caribbean (Smith, 1971, 502), any of which might have been used descriptively when the dance was being formed. The name has also been claimed to be derived from the Spanish word for 'Carousel' (Morris, 1969, 1134).
The rural form of the Rumba in Cuba was described as a pantomime of barnyard animals, and was an exhibition rather than a participation dance (Ellfeldt, 1974, 59). The maintenance of steady level shoulders while dancing was possibly derived from the way the slaves moved while carrying heavy burdens (Rust, 1969, 105). The step called the 'Cucaracha' was stomping on cockroaches. The 'Spot Turn' was walking around the rim of a cartwheel (Rust, 1969, 105). The popular Rumba tune 'La Paloma' was known in Cuba in 1866 (Sadie, 1980, 10/530).
The Rumba was introduced into the U.S.A. in the 1930's as a composite of this rural Rumba with the Guaracha, the Son, and the Cuban Bolero (unrelated to the Spanish Bolero) (Ellfeldt, 1974, 59). It was particularly popularised in 1935 by George Raft, who played the part of a suave dancer who wins the heart of an heiress through dance, in the movie 'Rumba', although the male dancing was done mainly by Frank Veloz.
The British dance teacher Pierre Margolie visited Havanna in 1947 and decided that the Rumba was danced with the break step on beat 2 of the bar, rather than on beat 1 as in the American Rumba. This is not entirely true, as the 'beat' of the music is traditionally determined by the rhythm of the Claves (two sticks being hit together). The Claves are hit on half-beats numbers 1,4,7 in the first bar of a two-bar phrase, and half-beats 3,5 of the second bar. Counting full beats, these correspond to beat 1, the half beat before 3, and beat 4 of the first bar, and beats 2 and 3 of the second bar. Ideally one might dance 5 steps over the two bars to match the Clave beats. But instead it was decided to dance only on one of the bars of the Clave sequence. The American Rumba is danced on the first bar Clave beat. Pierre decided to use the second bar, stepping on beats 2 and 3, and he added an extra step on beat 4 for no obvious reason. He brought this back to Britain, together with many steps he learned from Pepe Rivera in Havanna. These steps together with dancing the break on beat 2 rather than beat 1, after many years of heated debate in the 1940's and 1950's, became part of the standard International Cuban Rumba. (Lavelle, 1975, 1).
With only a transfer of weight from one foot to the other on beat 1 of each bar, and the absence of an actual step on this beat, the dance has developed a very sensual character. Beat 1 is a strong beat of the music, but all that moves on that beat are the hips, so the music emphasises the dancing of the hips. This together with the slow tempo of the music (116 beats/minute) makes the dance very romantic. Steps are actually taken on beats 2, 3, and 4. Weight tranfer and turns are performed on the intervening half beats. Again, as in the Samba, the weight is kept forward, with forward steps taken toe-flat, and with minimal movement of the upper torso throughout. (source: History of Latin American Dancing)
Fundamentals of Rumba