The militants espouse a radical, puritanical strain of Sunni Islam whereby all shrines or holy sites that honor beings lesser than their God are considered apostate.
But as The Post's Loveday Morris reports, the extremists aren't only attacking the sites. They also "have been quietly selling off smaller antiquities from Iraq and Syria, earning millions of dollars in an increasingly organized pillaging of national treasures."
The jihadists' hatred and destruction of ancient artifacts, shrines, statues, even mosques, often recorded and then distributed on social media, have caused global outrage. Here is a look at some of the sites that were destroyed.
When the Islamic State took control of Palmyra in May, many feared this would signal the destruction of an archaeological treasure thousands of years old.
According to Liz Sly, "the 1st-century Temple of Bel lay at the heart of the complex of ruins that had made Palmyra one of Syria’s most significant archaeological and tourist attractions," making it a UNESCO world heritage site.
The destruction of the tomb of the prophet Jonah was one of the first major atrocities against a historic site carried out by the Islamic State, and it "brought a new level of resentment," wrote Morris, one that the lack of electricity and water had not yet caused in the month after the Islamic State seized control of the city.
In what the United Nations' cultural agency deemed a "war crime," the Islamic State used heavy military vehicles to bulldoze the 3,000-year-old Nimrud archeological site, crushing relics from one of ancient Mesopotamia’s greatest cities.
The famous landmark, discovered in the last century, was known for its "pre-Islamic cultural heritage." According to a Post story from March, when footage was released of the destruction:
The second capital of the ancient kingdom of Assyria, Nimrud was built about 1250 B.C. and destroyed in 612 B.C. At its height, it was the center of one of the most powerful states at the time, reaching through modern-day Egypt, Turkey and Iran.
Militants used weapons to attack Hatra, an ancient fortress city in northern Iraq.
Video released by the Islamic State shows the militants pulverizing carvings, statues and walls, using guns, sledgehammers and pickaxes. In the footage, one fighter says: "Praise to God, who enabled us and the soldiers of Islamic State to remove the signs of polytheism."
"Until its ravaging at the hands of the extremists," Tharoor wrote, "Hatra was a remarkably well-preserved ancient site. It first rose to prominence in the 3rd century, probably as a garrison town for the Seleucid Empire, one of the quasi-Greek kingdoms that emerged after the death of Alexander the Great and the splintering of his short-lived empire in Asia."
In February, the Islamic State went to the Nineveh Museum in Mosul and used sledgehammers to smash artifacts that were known as some of the most cherished of pre-Islamic antiquity.
The jihadists' reasoning? In the video they circulated on social media, one fighter says:
"These statues, these idols, and these antiquities, when Allah, Glorified and Exalted be He, ordered to destroy and remove them, it was an easy matter. … We do not care even if it costs billions of dollars."
Note: This post was updated on Aug. 31 to include the destruction of Palmyra's Temple of Bel.