Before the creation of the sai in Okinawa, similar weapons were already being used in other Asian countries including India, Thailand, China, Vietnam, Malaysia, and Indonesia.
Some sources theorize that this weapon concept may be based on the Indian trisula, an ancient Hindu-Buddhist symbol[3] that may have spread along with Hinduism and Buddhism into South-East Asia.
In Okinawa the sai was used by the domestic police (ufuchiku) to arrest criminals and for crowd control.
Use of the sharp points, the main prong and the pommel is emphasized, as well as rapid grip changes for multiple fast stabs and strikes.
Because there is no morphological plural in Japanese, the word "sai" refers to either a single weapon or multiple.