Creation of Kodokan Judo by Dr. Kano unified multiple schools of jujutsu and, for the first and only time, created all-Japan martial art. Judo remains largely unified, thanks to Kodokan and IJF, but in the course of its history a few independent Judo styles branched out under different circumstances and they still growing under their own rules.
The reasons for branching ware of two sorts: (1) political and/or geographical separation from Kodokan (SAMBO and Brazilian jiu-jitsu) and (2) Judo sport competitions (Olympic Judo and Kosen Judo).
When each of those styles in the first group (SAMBO and BJJ) seen nowadays as independent martial art and/or combat sport on its own rights and often accepting their relation to Judo with many reservations and just as a personal background of the style founder, they are truly a part of the global Judo development. By rejecting Kodokan link SAMBO and BJJ preserving their organizational structure and business model. But the political interests of their federations have nothing to do with the styles themselves.
The second group (Olympic and Kosen Judo) on the opposite claiming to be the “true Judo” that are loyal to Kodokan haritage. That even when Olympic Judo is governed by IJF (International Judo Federation; Kodokan has significant influence, but not authority over IJF) as a combat sport and not a martial art, and when Kosen Judo was branched out by Dr. Kano himself as Japan-only combat sport style when he started to introduce Judo to the rest of the World.
Dr. Kano created Judo not from the thin air, but on the solid foundation of old Japanese jujutsu. When on July 24, 1905 majority of leading jujutsu school representatives agreed upon accepting Kodokan as their “umbrella” organization their schools overnight became “judo” schools. One of the conditions of this agreement was preservation of traditional technique of each school in the kata form. In fact, it took 50 more years for outside observers to stop calling Judo “jujutsu”. But a few of those old schools managed to survive on their own and a few more new "old” jujutsu schools ware established over time. Within spirit of July 24 agreement I see those schools as branches of Kodokan Judo.
Styles of Judo:
1. Kodokan Judo
2. Modern Olympic Judo
3. Kosen Judo
4. Brazilian jiu-jitsu
• Combat SAMBO
• Why SAMBO is a Judo style when..?
• SAMBO founding legend
6. “Old” Jujitsu
Judo Styles and Styles of Judo