Footage has emerged of Islamic State group extremists taking sledgehammers and pickaxes to ancient Assyrian artifacts at the Mosul Museum in Iraq. In the video, dated February 2015 and published online by the Islamist group, militants can be seen knocking over statues dating back to the Assyrian Empire, which thrived in the region between 2500 B.C. and 605 B.C. Some of the artifacts were 3,000 years old.

The terrorist group formerly known as either ISIL or ISIS has occupied the museum since last summer and previously threatened to destroy its artifacts, which it indicated are inconsistent with Islam. "These ruins that are behind me, they are idols and statues that people in the past used to worship instead of Allah," one Islamic State group militant says in the video. "The Prophet Muhammed took down idols with his bare hands when he went into Mecca. We were ordered by our prophet to take down idols and destroy them, and the companions of the prophet did this after this time, when they conquered countries."

At least one Mosul source said the Islamic State group began burning the museum's priceless collection of rare books and manuscripts this month, according to the Independent. More than 100,000 documents reportedly went up in flames. The collection also included works from the Ottoman Empire period, some of which were registered with Unesco.

The ancient Mesopotamians once occupied present-day Iraq. Located between the Tigris and Euphrates rivers, the region was widely considered a cradle of civilization. Their artifacts have both cultural and historical significance.