"The Little Drummer Boy," originally known as "Carol of the Drum," is a popular Christmas song written by the American classical music composer/teacher Katherine Kennicott Davis in 1941. It was recorded 1955 by the Trapp Family Singers and further popularized by a 1958 recording by the Harry Simeone Chorale.
The song as published by Davis was based upon a traditional Czech carol. Davis' interest was in producing material for amateur and girls' choirs: her manuscript is set as a chorale, the tune in the soprano with alto harmony, tenor and bass parts producing the "drum rhythm" and a keyboard accompaniment "for rehearsal only". It is headed "Czech Carol freely transcribed by K.K.D", these initials then deleted and replaced with "C.R.W. Robinson", a name under which Davis sometimes published.
Although Davis did search far and wide for suitable material, the Czech original has never been identified, though the style is comparable with the Czech "Rocking Carol", a lullaby collected in the early 20th century by a Miss Jacubickova as "Hajej, nynjej"* and given English words by Percy Dearmer for The Oxford Book of Carols in 1928.
lots more : http://en.wikipedia.org/wiki/The_Little_Drummer_Boy
*the only track i found on lastfm sounds quite different
Hajej Nynej (Shepherd's Rocking Carol)