[4] Later, having reverted to Roman hands, Emperor Diocletian (r. 284–286) further enforced Circesium into a strongly fortified outpost on the far eastern frontier of the empire, in order to improve the defensive capabilities against the Sasanians.

[4] According to contemporary sources, the cenotaph of Emperor Gordian III (who had been killed during his own Sasanian campaign of 244), was still visible at Zaitha (which was located nearby Circesium) when Julian and his army moved through the area.

[4] Joseph Wiesehöfer / Encyclopædia Iranica notes that this might have been one of the reasons why Sasanian King Khosrow I (r. 531–579), during his offensive in 540, decided to invade the Roman Empire further to the north, "along the western bank of the Euphrates".

[4] During the flight of Khosrow II (r. 590–628) in 590 from Sasanian territory during the rebellion of Bahram Chobin, he was briefly sheltered by the Byzantine garrison commander of Circesium, Probus, before moving to Hierapolis.

[6] In the late 9th century, the autonomous governor of Egypt, Ahmad ibn Tulun, extended his domains as far as Circesium, but the Abbasids under al-Muwaffaq recaptured it in 881.

[6] The city, alongside nearby al-Rahba, played an important role in the struggles involving the Hamdanids who ruled the Jazira autonomously during the 10th century.

[8] Due to its strategic location, Muslim geographers throughout the Islamic era mentioned Circesium but gave no detailed account of the city in their descriptions of the region.

[6] Writing in the early 20th century, historian M. Streck wrote that al-Busayra was a village of thirty to forty clay houses adjacent to a large site of ruins.

Abrahamius, took part in the Council of Chalcedon in 451 and was a signatory of the joint letter that the bishops of the province of Osrhoene sent to Byzantine Emperor Leo I the Thracian in 458 regarding the murder of Patriarch Proterius of Alexandria.