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Nearly a week after recapturing Palmyra from ISIS, Syrian forces say they’re uncovering grim evidence of how the Islamist terror group conducted its 10-month occupation of the ancient city.

A picture shows people walking near the remains of Arch of Triumph, also called the Monumental Arch of Palmyra, on March 31, 2016, in the ancient Syrian city of Palmyra, which was destroyed by jihadists of the Islamic State group in 2015. (Credit: Joseph Eid/AFP/Getty Images)
A picture shows people walking near the remains of Arch of Triumph, also called the Monumental Arch of Palmyra, on March 31, 2016, in the ancient Syrian city of Palmyra, which was destroyed by jihadists of the Islamic State group in 2015. (Credit: Joseph Eid/AFP/Getty Images)

The liberating forces found a mass grave with at least 40 bodies — many of whom were women and children — in the northeastern part of Palmyra this week, the state-run Syrian Arab News Agency reported.

The dead are believed to have been among hundreds killed by ISIS after it stormed into the central Syrian city in May, SANA reported.

Some of the remains show signs of beheading and torture, SANA said.

The Syrian army and militias loyal to the regime seized the city and chased out ISIS fighters on March 27, state-run media said. Since then, the government has been trying to assess the death and destruction that the group left behind.

Palmyra, in the Homs countryside northeast of Damascus, is a place of ancient ruins that are considered to be among the world’s most treasured, and is recognized by the United Nations as a World Heritage Site.

ISIS demolished some of the ruins, including the 1,800-year-old Arch of Triumph and the nearly 2,000-year-old Temple of Baalshamin. ISIS also beheaded the antiquities expert who looked after the ruins.

Palmyra was a caravan oasis when Romans overtook it in the mid-first century. In the centuries that followed, the area “stood at the crossroads of several civilizations” with its art and architecture mixing Greek, Roman and Persian influences, according to UNESCO, the U.N. agency that documents the world’s most important cultural and natural sites.

Syrian government forces have been battling militant groups including ISIS in a five-year war that has torn the country apart. The war has killed more than 250,000 people, left 1 million injured and displaced millions since the bloodshed began in 2011, according to the United Nations.