The question is, do we know the elaborate, yet very interesting, story of how our wonderful Brazilian Jiu Jitsu belt system came to be? Probably not.
But, we should. Ours is a martial art and sport that is really quite young with a relatively short history. One of its two co-founders left us less than 4 years ago. We held our world championships for the first time in 1996. So, in the scheme of things (say, compared to hundreds of years for some other forms), there's not even that much to know.
If you train BJJ, you probably have a belt rank. And, now it's time to do some learnin' about how that came to be from Pedro Valente Jr., of Valente Brothers Jiu Jitsu (headquartered in Miami, Florida). The Valente family is 1st generation BJJ (with 3 generations involved in the art). Pedro Sr. is a red belt and Grand Master. These guys know Jiu Jitsu and are as close to its history as possible. So, have at it already. And, remember, there will be a test, so don't half ass this one.