In 1997 Penn began training Brazilian Jiu-Jitsu under
Ralph Gracie, eventually earning his purple belt from Gracie.
[19] At that point he moved to
Nova União, where he was eventually awarded his black belt in 2000 by
Andre Pederneiras.
[19] A few weeks later, he became the first non-Brazilian to win the black-belt division of the
World Jiu-Jitsu Championship held in
Rio de Janeiro,
Brazil.
[20] While Penn's most well-known and prestigious achievement was placing first in the black belt division in the 2000 world championships, he had success at the Mundials in previous years. In 1999, at the age of 20, Penn finished 3rd, earning himself a bronze medal in the brown belt division, losing only to
Fernando "Tererê" Augusto, and in 1998, earned a silver medal, placing 2nd in the blue belt division.
[21] Penn is thought to have earned the fastest legitimate black belt of all active Brazilian Jiu-Jitsu practitioners. (wiki)
-In other words, he was just really good