A famous Japanese Judoka comes to Brazil. Teaches Japanese Jiu Jitsu to a guy named Carlson Gracie. Carlson's brother, Helio, is not strong enough to excel in some of the techniques, so he adapts what he has learned to a smaller frame with new moves.

Carlos couldn't teach a lesson one day, so Helio ended up being the substitute. The lesson went so well, that the student asked that Helio be his main teacher now. Helio developed his own system of submission grappling that became known as Gracie Jiu Jitsu aka Brazilian Jiu Jitsu, but it didn't really achieve prominence worldwide until 1993 when Helio's son Royce displayed it for the world at UFC 1.

Although they share a similar name, Brazilian Jiu Jitsu (BJJ) has many differences from Japanese Jiu Jitsu to the point where they are completely separate martial arts.

Sources: The Fighter's Mind-Sam Sheridan. Also here is an interview with Helio translated from Portuguese http://www.global-training-report.com/helio2.htm