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.
The saihai were initially employed during the 1570s and 1590s, spanning the Genki and Tensho year periods. The need for effective communication between commanders and troops in the heat of battle necessitated the use of these signals.