In Syria’s ancient city of Palmyra, the Islamic State is finishing a job that four years of violent conflict got started.

The Islamic State has become infamous for destroying historical artifacts in land it controls, from the Mosul Museum in northern Iraq to the ancient Assyrian city of Nimrud. When Islamic State militants overran Syria’s ancient city of Palmyra in May, it seemed that another of the world’s great cultural treasures would be lost.

On Sunday, those fears were confirmed when observers reported that the Islamic State had used explosives to blow up part of the 2,000-year-old Temple of Baalshamin, one of the most important sites in Palmyra. The news came just days after the Islamic State executed Khalid al-Asaad, 83, who had served as Palmyra’s chief of antiquities for a half-century.

But there’s one thing many reports neglect to mention about Palmyra: The four-year-long Syrian conflict has been quietly destroying it since even before the Islamic State, also known as ISIL or ISIS, came on the scene.

In April 2013, Reuters reported that Palmyara’s ruins were being damaged in fighting between rebels and forces loyal to Syrian President Bashar Assad. According to witnesses, rebels were moving in and around the archeological sites and Assad’s army fired at them with rockets, mortars and artillery shells. The Syrian Ministry of Culture’s director of antiquities and museums also admitted to Reuters that “the Syrian army is in some areas in the archeological site and we oppose this.”

UNESCO, too, has been warning about damage to Palmyra, a world heritage site, for two years or more. The ancient city, which the United Nations’ cultural organization calls an “oasis in the Syrian desert” that contains the “monumental ruins of a great city that was one of the most important cultural centers of the ancient world,” has been officially listed as “in danger” since 2013.

In a January 2014 world heritage progress report to UNESCO, the Syrian Ministry of Culture detailed the effects of conflict in and around the site, which included, according to UNESCO’s summary:

And that’s according to the Syrian government itself. UNESCO hasn’t been able to visit the site since March 2011. But based on other sources, including satellite imagery, UNESCO says the government continued to use the site as a base of military operations until it was captured by the Islamic State in May.

It wasn’t just shelling and military vehicles doing damage. The conflict has created ideal conditions for looting artifacts and made it impossible to do the kind of regular maintenance that ancient sites like Palmyra need.

In a video statement released in May, UNESCO Director-General Irina Bokova said she was “extremely worried” about the developments in Palmyra, referring to the pillaging of Mosul and Nimrud. But she also noted that she’d previously requested that the Syrian military cease operations there. “Unfortunately, we have seen this last two years some damages made. Palmyra was converted into a military camp. We have seen columns fallen and damage also to the palm groves that are adjacent to the area.”

There’s no denying that Islamic State militants take particular delight in destroying cultural symbols, but remember: As the Islamic State levels parts of Palmyra and erases another piece of human history, they’re just finishing what Assad, other rebel groups, and four years of conflict have started.

This article originally appeared in GlobalPost. Its content was created separately to USA TODAY.