Ask someone what Philadelphia is known for and they are likely to answer cheesesteak, the declaration of independence or the Rocky films starring Sylvester Stallone. It is a safe bet they won’t say black cowboys.

Or a self-described black cowgirl like Ivannah-Mercedes. “When I tell people I ride horses, they’re like, ‘Here, in Philadelphia? Where are the horses?’” she says. “But when people see me on the horse in Philadelphia, it usually involves cameras and ‘Oh, my goodness, can I pet your horse? And where’d you guys come from?’

Ivannah-Mercedes is a member of one of the black horsemanship communities that thrive, often unseen and unsung, in cities across the US. She also makes her acting debut alongside Idris Elba in a new film about black riders in Philadelphia that looks set to give their way of life fresh recognition and respect.

Concrete Cowboy, which premiered last year at the Toronto film festival and is now available on Netflix, is a gritty drama about a father-son relationship set around the Fletcher Street Stables, one of the first stables in inner-city Philadelphia and now among the last.

It dates back more than a century to when horse-drawn wagons delivered produce, laundry and milk. That era drew to a close in the late 1950s when cars and trucks took over but the historic barns survived as a precious community focal point and safe haven – often without the knowledge of city residents living just a few miles away.

Ivannah-Mercedes’s great uncle was a rider at Fletcher Street in the 1950s and 1960s and took her mother there and to other stables, “so it’s just passed down from generation to generation”, she recalls. Ivannah-Mercedes has been riding since she was first able to sit up and took her first professional lesson at the age of eight.

“It’s just pure freedom. Horses in and of themselves are just very majestic creatures and once you really get to know them and the ins and outs and their brain, the way they think, the way they communicate with each other, it’s a beautiful experience to be working with them but riding them is almost indescribable. It’s the freedom that I wish everyone could experience.”

She adds: “This is the city. People think horses and they think country and they think Texas, lots of land. But with horses, if you can find a space, as long as you’ve got the time to dedicate to your horse, horses can live anywhere.”

The film follows Cole (Caleb McLaughlin), a troubled 15-year-old who, expelled from school, is sent by his mother to live with his estranged father, Harp (Elba), who rehabilitates horses at the Fletcher Street Stables. The story conveys how horsemanship can give isolated young people a sense of purpose and self-worth.

This rings true to Ivannah-Mercedes. “My nephew has a hard time focusing everywhere,” she says. “He’s always getting yelled at: ‘Focus, focus, focus!’ But when we’re at the barn and in that ring and he’s on that horse, that’s all he cares about. He’s focused, he’s dedicated and he wants to accomplish things.

“He wants to understand his horse. It’s beautiful. So I can definitely say that I’ve seen first-hand how much horses can cause a person who is not focused on a regular basis to just focus and really get things done.”

It’s a world away from the classic movie image of a white cowboy such as John Wayne or Clint Eastwood riding across vast open plains. In fact a quarter of American cowboys were black, according to historians. The word “cowboy” was a racist term for a black ranch worker.

Ivannah-Mercedes comments: “Then we got the John Waynes in the world and everybody said, ‘Oh, well, I guess cowboys are not dirty people, they’re fun and interesting and they have skills.’ And so along the lines it transferred into something admirable and something that people wanted and then I think when that happened, that’s when it washed out.”

And how unusual is she as a woman in this community? “In the movie, you’ll see very few female characters and that is fairly accurate of what you will find in most urban equine settings. There’s not many women; it’s kind of a boys’ club and the women that you find are very strong women. They hold their own because they have to and they’re remarkable.”

Concrete Cowboy is directed by Ricky Staub and based on a novel, Ghetto Cowboy, written by Gregory Neri, who first heard about the stables in 2008 when a friend sent him a link to a Life magazine article about Fletcher Street.

Speaking by phone from Vienna, Austria, Neri said: “The first image I saw was this young black kid standing on the back of a horse in the middle of the inner city and I had the reaction that most people have: what is this?

“I’ve been all over the United States, have been in all kinds of neighbourhoods, but as I flicked through these photos with black cowboys, I’d never seen a place like this. It looked like some kind of modern-day western or something.”

Neri’s research led him to Fletcher Street where he talked to riders and collected stories about the community. “It was clear to me it was a great place to set a story. It fit everything I like writing about which are hidden figures, peoples and communities that nobody knows about that have literally been kind of erased from the bigger history of American stories.

“Even people I knew in Philadelphia who lived a couple of miles away had no idea what was going on here because most people’s perception was, ‘Oh, this is a very dangerous neighbourhood. I’m never going to go there and that’s it.’ It was a very negative perception.

“When I saw what was going on with these guys who were saving horses and then also saving young kids by giving them horses and leading them into this world, to me it was something worth celebrating and something worth showing to people: this is something that exists. It could be right nextdoor to you and you have no idea.”

Neri, 57, discovered what impact this subculture can have on young people who might otherwise go astray. “There is a lot of gang activity and things like this going on in these neighbourhoods. Their idea was if you give a kid on the street a horse, that can change your life because owning your own horse is a full-time job. You’re there before school, you’re there after school, you’re there at weekends, you don’t have time to get into trouble.

“Then for a young kid to get up on this big animal literally changes their perspective because you’re seeing it from up high and, in a tough neighbourhood, you get instant respect because when people literally have to look up to you, nobody’s going to mess with you when when you’re on a horse.

“How these kids are judged is on how well they take care of their animals so if they feed them well and they groom them well and they ride them, that’s good props on them and if they don’t, it makes them look bad from the horse community. So it really instils them with a sense of self and pride and all these good things you want young people to be exposed to.”

It’s a timely release as some stables continue to succumb to gentrification and even the Fletcher Street Stables faces an uncertain future. The vacant area that its riders used for a long time has been lost to developers, leaving it to search for a permanent home. The makers of Concrete Cowboy have helped create a non-profit organisation to raise funds for an equestrian centre.

Neri adds: “One of the things I hope the book and now the movie does is change the perception not only among people but from the city itself and how the media talks about it – the whole idea of changing the narrative. Now it feels like we want to encourage that this is something to be celebrated and treasured as opposed to trying to erase it. So turn it into a positive for the city as a whole.”

The hopes of such communities rest with a new generation personified by Ivannah-Mercedes, who both on screen and in real life displays resilience and good humour. She laughs as she describes her current ride, a horse called Mimi that belongs to her best friend.

“I nicknamed her the Apocalypse Horse because this horse can literally do anything and, when the apocalypse comes, I’m going to take her and saddle her up, saddlebags and all, and she will get me anywhere. That horse will run for miles and days. She can scale mountains straight up in the air. I love that horse.”

• Concrete Cowboy is available on Netflix now