According to Okinawan folklore, the sai began as an agricultural tool used to measure stalks, plow fields, plant rice, or to hold cart wheels in place. It may have also been an evolution from a pitchfork but evidence for this theory is limited. Before its arrival on Okinawa, the sai was already being used in several other Asian countries including India, Thailand, China, Vietnam and Malaysia.
Outside Okinawa, the sai is generally believed to have been designed as a weapon. Early evidence suggests Indonesia as the weapon’s point of origin where it is said to have been developed from the trisula. The word trisula itself can refer to both a long or short-handled trident. Because the trisula was created in South Asia, another theory is that the sai originated in India and spread along with Hinduism and Buddhism. This is supported by the fact that the trisula is important as a Hindu-Buddhist symbol.
The sai eventually reached Japan in the form of the jitte or jutte, which has only a single prong. Both are truncheon-like weapons, used for striking and bludgeoning.
