Now some Yazidi girls who had to abandon their old lives to escape the militants' clutches have been given a new chance, thanks to a photography workshop in their refugee camp.
Some of those taking part in the classes were captured when ISIS militants laid siege to Iraq's Mount Sinjar
in August 2014. Abused by the fighters, they are now trying to heal, and rebuild their lives.
The project, run by UNICEF and funded by the Italian government, helps empower the displaced young women to express themselves, using pictures they've taken in their new home.
Meeting every day for two months, they were taught photography techniques by two Kurdish photographers before exploring the camp, cameras in hand.
The resulting images tell stories of tragedy and sadness, but also of resilience and strength.
Nisreen, 19, says she chose to photograph a model of "a sacred place" of huge importance to Yazidi people
: Lalesh, in Iraq's Nineveh province -- a place of pilgrimage, and home to the Yazidis' holiest temple.
"This place is called Lalesh -- there are sacred Yazidi graves here that people visit," she explains.
Others chose to focus on the people living inside the camp.
In a nod to their shared heritage, Barfe, 18, trained her lens on a woman in Yazidi dress -- white robes and a colorful head covering.
"The clothes she is wearing are traditional Yazidi clothes and that is why I chose to take a photo of her," she explains.
Safiya, 14, picked out an image of a fellow refugee with a "sad facial expression" as her favorite. "She had been carrying water and was tired so I took a photo of her -- there is fatigue in her face," she says.
While 19-year-old Zina snapped a photograph to illustrate the resilience of the refugees: A woman determined to keep working, despite being forced out of her home.
"I took it in a dressmaking course; this woman was working as a tailor, [and] she hasn't given up."
The workshop's organizers say it has made a huge difference to the participants, motivating them and boosting their confidence.
"Bushra is an entirely different person," says Nuha Serrac, coordinator for the workshop, talking of another girl in the class. "At first, if we asked her a question, her face would go red as a tomato.
"She wouldn't even lift her head to give a response. Now look at her, she's walking up to people on her own and taking their picture."
When Safiya confided to her photography instructor that she wasn't going to the UNICEF-supported school, she was told she couldn't take part if she wasn't in lessons. The ultimatum helped convince her father to let her attend the school, which is housed in a tent in the camp.
The camp -- CNN is not naming it or revealing its location, to protect those living there -- is home to almost 20,000 people. More than half of the residents are children up to the aged of 17.
The United Nations estimates that hundreds of girls and women are still missing, and presumed to be being held by ISIS as sex slaves.
But for these lucky few, there is hope -- and a possible career path -- in the future.
"I am Nisreen. I am a photojournalist," the teenager says proudly.
"My name is Barfi. I am a photojournalist," her classmate echoes.