Sanjo refers to the playing of an instrument solo to the accompaniment of janggo (hourglass-shaped drum), moving from slow to fast rhythm, in four to six movements. Gayageum Sanjo is Korean instrumental folk music played solo with Gayageum (twelve-stringed zither). Gayageum Byeongchang refers to the singing and playing of Gayageum at the same time. All Sanjo start with slow rhythm and gradually changes to faster rhythm, making listeners feel tense and increasingly delighted. Gayamgeum Sanjo is made up of four to six rhythms: jinyangjo (slow), jungmori (moderate), jungjungmori (moderately fast), jajinmori (fast), and hwimori (fastest). Compared to other instrument-based Sanjo, Gayageum Sanjo masters could form diverse schools thanks to the unique characteristics of Gayageum. A singer engaging in Gayageum Byeongchang sings a part of danga or pansori to the accompaniment of his/her own Gayageum playing. Gayageum Byeongchang used to be sung by Gayageum Sanjo masters, but the current tendency is for the separation between players of Sanjo and Byeongchang. A song sung as Byeongchang creates its own atmosphere due to the unique melody of Gayageum. The following are well-known parts of Gayageum Byeongchang: Jebinojeonggi (Route of the Swallow's Trip) of Pansori Heungboga (Song of Heungbo), Sarangga (Song of Love) of Chunhyangga (Song of Chunhyang), Gogocheonbyeon (Brightness of the Sunshine in the Sky) of Sugungga (Song of the Rabbit and the Turtle), and “Sim Cheong’s Father on His Way to Hwangseong” of Simcheongga (Song of Sim Cheong).