Before they were famous: BJJ white belt vs. Judo black belt in Judo competition
Although it cannot be stated precisely, according to some historians, Jiu Jitsu or Jujutsu was born in India and was practiced by Buddhist monks. With the expansion of Buddhism, Jiu Jitsu spread from Southeast Asia to China, finally arriving in Japan where it developed and gained further popularity.
In Japan, Jigoro Kano coined the term Judo in order to distinguish from the old Jujutsu:
It was necessary to improve the old jujutsu, to make it accessible to all, change its goals that were not meant for physical education or moral values, much less for intellectual culture.
He developed a sport, gathering some less dangerous techniques of jiu jitsu. Judo involves self-defense techniques (Goshin-Jitsu), ground fighting with chokes and submissions (Newaza) and kicks and punches techniques (Atemi-Waza) – these last two trained only by black belts, and usually in the form of Kata.
It is safe to say that Judo and Jiu-Jitsu have a lot in common. They differ especially regarding the rules of competition. We often see athletes competing in both sports as in this video, which showed the former UFC lightweight and welterweight champion BJ Penn back when he was a white belt in Brazilian Jiu Jitsu in a black belt Judo tournament.
BJ Penn pulled guard and tried an armbar, but apparently, his opponent shook it off. Then, he got a takedown and took the back, put the hooks in and flattened the judoka out.
Penn went for a double leg and successfully got to full mount then transitioned to the back. He tried to reverse to an armbar, but the judoka rolled his way out. After that, BJ Penn got a submission and the following events can be summarized in a single word: domination.
Clearly, Penn used Jiu Jitsu techniques in what was meant to be a Judo tournament, and the video triggered controversy. Addressing the issue about fighting a black belt in Judo, BJ Penn stated on a podcast (at 41:56):
Now I look at it like, if you want respect against a Judo black belt you gotta try to beat him in judo, it’s not fair to bust out jiu jitsu against them. Cause it’s different.(…) I’ve been doing a lot of Judo lately, and now I look back on that and I am a kind of embarrassed about that tape.