The word sanjo literally means scattered modes and refers to the fact that these pieces employ a variety of rhythmic and tonal modes. When court musicians first heard these sanjo pieces, they didn't think of it as music but rather a disorganised collection of scattered modes. Kayagum master Kim Chang-Jo is credited with creating the very first sanjo piece around 1890 and since then this solo instrumental form has been adapted for most other traditional instruments. The music relies heavily on improvisation and the most prominent musical characteristic is that the piece increases in tempo as it progresses through the various rhythmic modes. The accompaniment of the janggu is also important in establishing the rhythmic foundation for the instrumentalist. A sanjo is technically quite brilliant, particularly in the strident rhythms found in the final sections of the piece.