Notorious Irishman Conor McGregor has top billing at Madison Square Garden. Photo: Reuters/Joshua Dahl-USA TODAY Sports

It’s not often that you see a sport transform right before your eyes. But fans of mixed martial arts are now witnessing some of the biggest changes the sport has ever seen in its short, but storied history.

Just 15 years ago the Ultimate Fighting Championship (UFC) was an organization heading toward bankruptcy, alongside a sport that to many was simply underground and violent.

United States senator John McCain once famously described mixed martial arts as “human cockfighting” and petitioned governors of all 50 US states to ban UFC events. But fast forward to 2016 and mixed martial arts, along with the global MMA juggernaut UFC, is an entirely different beast.

In July this year, entertainment giant WME-IMG announced a massive US$4 billion acquisition of the UFC, along with a consortium of investors from private equity firms Silver Lake Partners, KKR and veteran Hollywood agent Ari Emanuel.

Three months into the new management structure and some of IMG’s top entertainment clients — including Serena Williams, Sylvester Stallone, Ben Affleck and Mark Wahlberg — were drafted in as minority shareholders, a move that adds a touch of celebrity mojo to a sport in desperate need of a perception overhaul.

But 2016 will perhaps be remembered for a landmark agreement that saw a long-standing ban on mixed martial arts events in New York overturned.

The UFC will make its Madison Square Garden debut on November 12 with its biggest star, the notorious Irishman Conor McGregor, taking the main stage.

But it’s not just the markets of North America where this rapid change is taking place.

Asia, the spiritual heartland of martial arts, has emerged as the fastest-growing region for the sport, driven largely by the Singapore-based ONE Championship.

I want us to be as ubiquitous as NBL. If our plans go right, the next 12 months will cross that two billion homes mark

In the past 12 months, ONE has taken its brand of mixed martial arts to some of Asia’s fast-growing economies from Cambodia to Yangon and Jakarta to Bangkok.

Like the UFC, ONE has been a target for private equity investors, with Singapore government-backed hedge fund Heliconia Capital Management investing an undisclosed sum to help ONE Championship expand into new ground and increase the number of live events across Asia, especially in China.

Chatri Sityodtong, founder and chairman of ONE Championship, says that in fewer than five years, the organization has grown into a global brand with a broadcast reach to more than one billion homes across 118 countries. He was is bullish on its growth plans.

“I want us to be as ubiquitous as NBL,” Sityodtong says. “If our plans go right, the next 12 months will cross that two billion homes mark.”

In 2014, Filipino boxing fight icon and politician Manny Pacquiao became a strategic investor in ONE Championship and Manila has gone on be a hugely successful market for ONE.

So, yes, the story is one of considerable growth. But while mixed martial arts is now the world’s fasting growing sport, it is arguably the most misunderstood. The combination of cage fighting, shaved heads and tattoos don’t make for family-friendly TV viewing, but this too is set to change.

Breakout stars like Ronda Rousey, McGregor and Angela Lee, currently ONE women’s atomweight world champion, are bringing the sport a much more marketable image.

It’s hard to imagine any other sport in history that has attracted so much attention, gained so much notoriety and pushed so quickly toward mainstream acceptance.

Hold on to your seats, folks. It’s going to be a wild ride.

Matt Eaton is Managing Editor of The Fight Nation