In February 2015, Isis' social media channels circulated a video of men with sledgehammers destroying relics in the Mosul Museum.
Isis also intercut the film with footage to include songs about idol-smashing and praise of God.
The propaganda piece included a man in a black skullcap, who said to the camera:
O Muslims, these statues behind me are idols of people from previous centuries who worshiped them instead of God almighty.
If God has ordered their destruction, they become worthless to us, even if they are worth billions of dollars.
Fortunately, the artefacts were actually mostly worthless to everyone, with a few exceptions.
In early 2014, months before Isis seized Mosul in June, around 1,700 items of the 2,400 in the Mosul Museum collection, were moved to Baghdad.
This wasn't in anticipation of an attack, but because Mosul Museum was set for renovation.
So most of the statues smashed by Isis were in fact replicas made of plaster.
After two and a half years of Isis control, Iraqi government forces reclaimed the museum early this week.