The saihai first came into use during the 1570s and the 1590s between the Genki and Tensho year periods. Large troop movements and improved and varied tactics required commanders in the rear to be able to signal their troops during a battle.
During a time when large-scale military movements were common, the need for rapid communication between commanders and troops became increasingly important. The saihai signals played a crucial role in facilitating this exchange of information.