By 2014 ISIS had occupied great swathes of Syria's northeast and Iraq's north, and women from the Yazidi minority were being traded by IS soldiers for rape.
Among Syria's Kurdish communities, all-female combat teams had formed. Their stand against the terror group at Kobani is where journalist Gayle Tzemach Lemmon has drawn inspiration to tell their story.
Her new novel The Daughters of Kobani is also set to become a new TV series by a production company owned by Hillary and Chelsea Clinton.
Fighters from the Kurdish Women's Protection units (YPJ). Photo: AFP / FILE
Listen to the full interview with Gayle Tzemach Lemmon here
It all started in 2016, when a contact from one of her earlier novels drew her attention to these women, who were not only fighting against IS but also for equality, she says.
She took five trips to north-eastern Syria to spend some time with these women and learn more about them.
"From 2011 onwards, this group of Syrian-Kurds decided that they would be the ones who would have to defend their communities, never imagining that would become as international and global as it did."
They were shaped by their sense of Kurdish identity and fighting for their rights and followed the ideology of the PKK's Abdullah Öcalan, she says.
"Öcalan was of course as the centre of it because his ideology said to these women that the Kurds could not be free until women were free."
In 2013, the women fighters - who were under the male-led YPG militia that is PKK-aligned - broke off into their own brigade, called YPJ.
Kobani was a big deal for IS in a 2014 David versus Goliath showdown, Lemmon says, because it was the axis point between towns the group controlled and a chance to take more of the border.
"The truth is that that story did not start in Kobani, but the world caught up with it in that town.
"Certainly, they didn't expect, as one Syrian-Kurd group told me, the country bumpkins of Kobani to be the source of resistance."
The US had been seeking a force to aid in the fight against IS, Lemmon says, but to establish a relationship with the PKK-inspired group meant support for Öcalan, who was in a Turkish prison, and that could put a strain on its relationship with its NATO allies.
"The world cannot stop watching because at this point Shingal [massacre] has happened and it's just home to some of the unbelievable brutality we've seen as ISIS goes into the town.
"I hate to dwell on this because the Yazidi community is so strong, so resilient and have shown so much courage, but you can't underestimate what that meant to watch that play out in real time.
"And for people to watch that and to see if Kobani fell, was that going to be one more Shingal?"
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Lemmon also showcases the reality for a lot of these women fighters - like Rojda who has to pick up a phone call from her constantly worried mother as she fires her gun.
"I think sometimes we see women doing some remarkable things, and we see them as either superhuman or disconnected from the rest of the world, but I wanted people to have the chance to hear the stories I heard of women who were daughters and sisters and friends.
"They were maybe a couple of hours' drive at most from their family, who didn't really understand why they were always putting themselves at such great risk and so Rojda's mother calls right in the middle of the battle.
"She knows if she doesn't pick up - those of you from traditional communities will understand this - her mother will immediately think she's dead or something horrible happened and will start calling everyone else and so it was just better to actually pick up the phone then and answer."
There's a great deal to learn about the contribution of women in combat, she says.
"[The group] starts with the Syrian-Kurds then expands to include many more people across ethnic groups and it's still a fighting force that does a huge amount of fighting and dying as compared to its number and ends up losing by the end of the battle 10,000 people, men and women.
"I do have the privilege of staying in touch with them and talking to folks there, I think it's difficult, it's a challenging time, especially with Covid.
"But the push they started continues in terms of local self-rule, that is certainly - as they would say - imperfect but does have women at the heart of what it is attempting to do."
Gayle Tzemach Lemmon is also the best-selling author of Ashley's War and the Dressmaker of Khair Khana.