Origins of Okinawan Weapons, Chapter 2, Sai

[sirdarksol]

The sai has one of the more mysterious origins. There are some who claim that it was originally something like a pitchfork, used to toss around straw. Others say that it was used in planting rice seedlings.
There are also a couple of good arguments as to why these ideas don't necessarily work. First of all, Okinawan farmers didn't use straw the way European farmers did. Second, the only real planting use I've heard is making holes for the seedlings, and there are much more efficient ways to do this.
The final idea that I have heard seems to make more sense (not saying it's right, just that it makes more sense given the information that we have). The Okinawan fishing spear, or nunti, has a tip that looks like a sai with one tine facing backwards. It would have been useful to fight with, but the backward-facing tine presented a danger to the wielder with some strikes.
According to this theory, a blacksmith turned the one tine around to make it a better hand-held weapon (which also, incidentally, made the weapon better for catching a sword-strike).

[disgruntled]

interesting... i have heard the seed theory myself, but it never sat right with me... why would the one be longer?? this has shed some light on the topic

[DOCBROWN1705]

I like that theory, here is another that I find interesting, and that seems to make a lot of sense.

It (The Sai) is known to have been used in other parts of Asia before its use in Okinawa, most likely stemming from Indonesia. In Malay the sai is known as a chabang, meaning branch, and is thought to derive from the Indian trident. The chabang spread through of Indo-China, and south Asia through trade, and may have reached Okinawa from one or more of these places. In China it might have been known as the SanKuChu. despite all the theory's however, it will always be most associated with the Okinawan culture.

[sirdarksol]

That actually fits with the theory that I consider most likely. Nearly all of Japan and Okinawa's technology stems from mainland Asia, and then was improved upon out of necessity. In an area as small as Japan and with as few natural resources as Japan, efficiency is the number one priority.
So the Okinawans saw this trident, and realized that they could make a spear/gaff in a single unit. If you spear a fish and it doesn't stay on the forward facing tines, the backward facing tine can be used to haul the fish on board.