Among the most tragic losses of the many antiquities destroyed in Iraq by the Islamic State in Iraq and Syria (ISIS) has been the destruction of Iraq's seriously understudied medieval architecture. The demolition of the mausoleum of Imam Yahya ibn al-Qasim and the tomb of Imam Ibn Hassan Aoun al-Din wiped out two of Mosul's prominent medieval landmarks. When another explosion obliterated the Imam Dur mausoleum in Samarra, it wiped out the earliest example of a muqarnas dome in the world. While the destruction of medieval sites has received far less media attention than attacks on better known ancient sites such as Nimrud or Hatra, the loss of Iraq's medieval sites is perhaps even more tragic due to the relative lack of scholarly documentation. An example is the monastery of Mar Behnam and Mart Sarah, northeast of Nimrud. Destroyed only three months ago, its loss was barely noticed, sandwiched between the carnage at the Mosul Museum and the graphic demolition of Nimrud. History is usually older than memory, and the monastery of Mar Behnam is no exception. Excavations of a tiny tell next to the monastery have revealed remains dating back over 8,000 years ago to the Neolithic, along with later Assyrian remains.

Recorded history, however, does not find the site until the Sassanid period in the mid fourth century A.D. At this time, according to a popular legend not written down until eight hundred years later, a minor king named Sanharib ruled Nineveh. His son Prince Behnam had forty armed knights as his constant companions, but his daughter Sarah was afflicted with leprosy. One day Behnam was riding through the plains north of Nineveh on a hunting expedition, accompanied by his forty companions. The hunting party sighted a gazelle and gave chase, pursuing the animal up the side of Maqlub Mountain until the animal darted into a cave and disappeared.

Following the gazelle through the opening on foot, Behnam entered the cave and was surprised to see not a gazelle but an old man sitting inside. The hermit was Mar Mattai, a famous Syriac saint who lived on the mountain, and after he invited Behnam to sit down the two had a long conversation during which Mattai introduced Behnam to Christianity. Behnam promised to convert if Mattai could heal Sarah of her leprosy. Mattai promised that he could, and instructed Behnam to bring Sarah and meet him at another place. When Behnam and Sarah arrived, accompanied by Behnam's 40 cavalrymen, they found Mattai already waiting for them. The old hermit struck the ground with his staff and water flowed out. He commanded Sarah to wash in the water, and when she did so her leprosy was instantly healed. Behnam, Sarah and the 40 cavalrymen were all baptized on the spot.

Sanharib was none too pleased, and after repeated attempts to talk his children out of their new faith failed he ordered that they be put to death. Someone in the court tipped of Behnam, and he fled to the town of Qaraqosh with Sarah and the forty cavalrymen. Sanharib and his troops overtook them near there, but before they could slaughter them the earth opened up and swallowed Behnam, Sarah and the forty cavalrymen.

Sanharib was devastated, and eventually he also developed leprosy. Remembering how Sarah had been cured, his wife suggested he also visit Mar Mattai, and the king reluctantly agreed. Mattai cured him as well, and as a result Sanharib also converted to Christianity. He exhumed the bodies of Sarah and Behnam and reburied them at the site of the monastery. Sunk into the tell, the tomb became known as "al-Gibb" or "the Pit." Tradition dates Behnam and Sarah's death to December 10, 352. This tradition, however, was not written down until around the time the monastery was massively renovated in 1164, a seemingly improbable coincidence which has led some scholars to propose that the legend was first developed to explain the presence of a Syriac monastery in an area where the Assyrian Church of the East was traditionally dominant.

Regardless of the historicity of its patron saint, the site eventually became associated with miraculous healing, both at the tomb and at a spring three kilometers away which tradition attributed to the spring where Mar Mattai healed Sarah. The hill behind the tomb became associated with the mysterious Qur'anic figure al-Khidr, the "maker of things green" often associated with fertility and renewal. Adherents of the Yezidi faith also revered the site for its connection to Khidr, sometimes known as Khidr Elias. The diversity of religious traditions found in northern Iraq is demonstrated by the mixture of styles at the monastery. The interior of the monastery featured relief sculptures of Saint Behnam as a knight riding a horse, alongside arches, niches, and arabesques in fine Abbasid style. According to French scholar J.M. Fiey, "Among collections in situ of sculpture of the period of the Atabeg rulers of Mosul it has no rival; no study of Abbasid art can pass it by without mention." Inscriptions on the walls are written not only in Syriac and Arabic but also in Armenian, the work of Armenians who moved into the region in the fourteenth century following a pogrom in Erbil in 1310. But the most famous case of syncretism penetrating the architecture came in 1295, when Mongol leader Baidu Khan attacked Mosul and Irbil. A raiding party plundered the monastery of its treasures. After Rabban Jacob (the chief of the monastery) went to Baidu Khan to complain, the Khan agreed to return all the treasures. In gratitude the monastery added an inscription in Uighur above Mar Behnam's tomb asking "May the happiness and praise of Khidr Elias befall and settle on the Il-khan and the nobles and the noblewomen." The protection of the Khan helped the monastery survive and grow. In 1415 the monastery became the seat of the Maphrian of the Syriac Orthodox Church, second in importance only to the Patriarch of Antioch. The Maphrian moved in 1508, but the monastery continued to be the seat of a bishop until 1782. By the 1790s the site was abandoned, cared for only by the Yezidis who still revered it in the name of Khidr Elias. Eventually the Syriac Catholic Church took control of the monastery, but it was not until 1900 that monastic life resumed. In July 2014, ISIS fighters reached the monastery, where they ordered the monks to leave immediately. Forced to leave the monastery's relics behind, they walked several miles on foot before making contact with Kurdish troops. On March 19, 2015 ISIS fighters rigged the tomb of Mar Behnam and Mart Sarah with explosives and blew it up, completely leveling the structure. Gone is the unique architecture blending Muslim and Christian art, along with one of the Middle East's few inscriptions in Uighur. The destruction of the site fits both ISIS' targeting of Christians and Yezidis as well as the destruction of graves revered as shrines. It has also made Iraq and the world that much poorer.