When Carlos Santos first arrived in the UAE, there were maybe 200 people who truly knew anything about jiu-jitsu.
And, yet, when he returned to his home of Brazil last week after a nine-year stay in this country, there are more than 20,000 schoolchildren who take part in this sport every week, both boys and girls and from every background.
If an up-to-date history of UAE sport were to be written right now, Santos's name would feature as high as anyone.
The three-time jiu-jitsu world champion was supposed to be here for a month when he landed in January 2002. It is only now that he has decided to return to Rio de Janeiro to see what new challenges he can find.
Santos was originally invited to the UAE by Sheikh Mohammed bin Zayed, the Crown Prince of Abu Dhabi, who was and remains a keen fan of this particular martial art.
Sheikh Mohammed is also Deputy Supreme Commander of the UAE Armed Forces, and Santos's remit was to introduce jiu-jitsu to the armed forces and they would see what happened. Neither could have possibly guessed what path this journey would take.
Speaking before he returned to Brazil, Santos said: "I am incredibly proud of the work we did in the UAE. There are now 20,000 kids in schools who are involved in jiu-jitsu every week, when none took part in the sport when I first got here.
"Plus it is one of the most popular sports with Emiratis when less than 10 years ago jiu-jitsu was nothing here.
"That is my legacy and it's something that will live with me forever. I wanted to make the UAE one the world's top countries for jiu-jitsu and we did that.
"A lot of praise must go to Sheikh Mohammed who was so supportive of everything I tried to do. I cannot thank him enough. He helped make jiu-jitsu mandatory in public schools [called school-jitsu], and by 2015 there will be over 500 schools all across the Emirates where our sport will be.
"When I first got here, it didn't exist at all. If you even said 'jiu-jitsu' to someone, they had no idea what you were talking about.
"It has been an amazing nine years, although I would have sworn at the time that I was only going to stay for a month.
"Jiu-jitsu is more than just a way for these kids to get fit and stay healthy. It is about respecting others and bringing people together. I would like to think I have done that in the UAE and, if I ever return one day, I'm sure the sport will be even bigger."
Santos became the Emirates' team coach and also created other tournaments here, all from scratch, such as the Abu Dhabi International Jiu-Jitsu Cup which, attracted the biggest names in the sport to the 2011 championship in April.
But it is the work he did in schools for which he will be best remembered in the years to come.
Santos said: "The fact so many Emirati girls fell in love with the sport gives me immense pleasure because that was not so easy to see when we started in the schools.
"The most important thing is that the families supported them and there are hundreds of girls who are getting so good.
"It won't happen right away, and indeed it might take a few years for lots of reasons, but I can envisage a day when a female world champion is a UAE national."
Santos's grand farewell to the UAE was April's World Professional Jiu-Jitsu Cup in Abu Dhabi.
Emirati Faisal al Ketbi, 24, who fought for the UAE at the tournament, is proof of the success of his Brazilian mentor's personal quest.
Al Ketbi said: "Carlos was an incredible coach and did great work in our country. I saw for myself how hard he worked to get things done and he would never, ever take no for an answer.
"It is not always easy to persuade people in the UAE to try new things, but he is not the kind of man who takes no for an answer and gave everything he had to get as many involved as possible.
"I don't know whether I would have had the opportunity to become involved in jiu-jitsu if I hadn't been given access to it at school. Carlos is one the most important people of all time in UAE sport."
Not a bad legacy at all.