Circesium

Circesium ( ', ), known in Arabic as al-Qarqisiya''', was a Roman fortress city near the junction of the Euphrates and Khabur rivers, located at the empire's eastern frontier with the Sasanian Empire. Procopius calls it the "farthest fortress" (φρούριον ἔσχατον) of the Romans. It was later conquered by the Muslim Arabs in the 7th century and was often a point of contention between various Muslim states due to its strategic location between Syria and Iraq. The modern town of al-Busayra corresponds with the site of Circesium.

==Etymology and location== The name Circesium or castrum Circense is of Graeco-Roman origin and translates as "the castle with the circus". Qerqusion (also spelled Qarqūsyōn) and al-Qarqīsiyā (also spelled 'Qarqīsīā) are the Syriac and Arabic versions of the Latin name, respectively. The Parthian transliteration, attested in Shapur I's inscription at the Ka'ba-ye Zartosht, is Krksyʾ. The etymology of the name was known to the medieval Muslim geographer, Hamza al-Isfahani, who wrote al-Qarqīsiyā stemmed from qirqīs, the Arabicized form of "circus". The ancient site was situated at the eastern bank of the Euphrates River, adjacent to the confluence of the Khabur River.