That's what I've been told about it, but this is the first time I actually read more accurate info.
It's interesting the way nunchaku was left outside of any traditional kata.
Any suggested reading about this subject?
Probably the best book ever written on the subject.
Unante - Secret Of Karate, by John Sells
http://www.wmhawley.com/products/books/unante.phpBtw, if you find the $55.00 price to be high, don't try Amazon. They are selling used copies for over $330.00
The nunchaku just wasn't a significant enough weapon when compared to the Bo, Sai and Tonfa. This is also why the "traditional" nunchaku kata are known by names such as Basic Nunchaku Kata or Kata #1 rather than bearing the name of a pre 20th century master like Sakugawa, Chatan Yara or Matsu Higa.
One needs to remember that back in Okinawa they were more interested in the utility of the weapon and had no interest in how cool it looked spinning around. The fact that you could strike somebody with a sai or staff without real concern of a bounce back made something like the nunchaku a less appealing weapon.
Had the nunchaku actually existed in China during the formative years of the next generation boxing styles (18-19th centuries) weapon use was advanced and sophisticated enough that forms (kuen) would have been devised for the weapon and it would have become part of the flexible weapon arsenal of those boxing styles along with three sectional staffs and whip chains. The only problem is it didn't exist in the Chinese arsenal of weapons. They had a two sectional staff but the usage and design was completely different.
Some people insist the nunchaku (or a Chinese version of the weapon) existed in the arsenal of some lesser known boxing systems and even suggest that is how it was introduced to Okinawa via Fukien transmission but it simply isn't true. Ironically both the sai and tonfa are of Chinese origin and stories of Okinawan "tool based" origins are made up folklore or were attempts at "cover stories" to explain the item to authorities. Although in the case of the sai this would have been rather futile because it was recognized nearly everywhere as a weapon.
Stories of the nunchaku coming from an Okinawan tool to thresh grain and rice seem to have been fabricated by Shinken Taira when he introduced Kobudo weapon systems to Japan in the 1920s. The whole "peasants turning farm implements into weapons of defense when swords were banned" is mostly folklore and likely exaggerated to make the system interesting enough to be embraced by the modern practitioners of this new martial art introduced to Japan during the 20s. Many Karate instructors (such as Funakoshi) omitted traditional weapons from their new karate programs because they felt they were outdated and of no interest.
Now obviously in some cases the "tools into weapons" story was factual when it came to weapons like the sickle (kama) and boat oar (eku). With things like the staff (bo) it is probably a little bit of both. And of course the nunchaku has it's origins in a horse bridle. For use as a practical weapon it was slightly modified. It also seems to have been developed as a weapon very late in the 19th century which would also explain why there are no extant (koryu) kata.
Horse bridle examples generally date to the mid to late 1800s which suggest the modified weapon we know as the nunchaku could be no older than those examples.