Sankyoku gasso developed in such a polyphonic way probably because there was much development in instrumental works, such as Jiuta's "tegotomono" (pieces with long instrumental interludes called "tegoto"), koto music's "danmono" (leveled pieces) and kokyu music's "honkyoku" (pieces composed in the early days).
このように三曲合奏が多音的な展開を見せたのも、地歌の手事もの、箏曲の段もの、胡弓本曲など器楽的な発展が著しかったからであろう。