Hellenistic and Byzantine Kallinikos
The Seleucid king Seleukos II Kallinikos (reigned 246–225 BC) founded ar-Raqqah as the eponymous city of Kallinikos (Latinized as Callinicum). In the Byzantine period, the city was briefly named Leontoupolis by the emperor Leo I (reigned 457–474 AD), but the name Kallinikos prevailed. In 542, the city was destroyed by the invasion of the Persian Sasanid Shahanshah Khusrau I Anushirvan (reigned 531–579), but was subsequently rebuilt by the Byzantine emperor Justinian I (reigned 527–565).
In the 6th century, Kallinikos became a center of Syriac monasticism. Deir Mār Zakkā, or the Saint Zacchaeus Monastery, situated on the tell just north of the city, today's Tall al-Bi'a, became renowned. A mosaic inscription there is dated to the year 509, presumably from the period of the foundation of the monastery. Deir Mār Zakkā is mentioned by various sources up to the 10th century. The second important monastery in the area was the Bīzūnā monastery or 'Dairā d-Esţunā', the 'monastery of the column'. In the 9th century, when ar-Raqqah served as capital of the western half of the Abbasid Caliphate, this monastery became the seat of the Syriac Patriarch of Antioch.
Early Islamic period
In the year 18/639, the Muslim conqueror 'Iyāḍ ibn Ghanm took the Christian city Kallinikos by contract. Since then, it figured in Arabic sources as ar-Raqqah, but still in Syriac sources the name of Kallinikos remained. In 20/640–1, the earliest congregational mosque in the Jazira was built in the predominantly Christian city. many companions of the Prophet Muhammad used to live in ar-Raqqah. The Battle of Siffin took place here and thus the tombs of Ammar ibn Yasir and Uwais al-Qarni are located in ar-Raqqah.
The strategic importance of ar-Raqqah grew during the wars at the end of the Umayyad period and the beginning of the Abbasid regime. Ar-Raqqah lay on the crossroads between Syria and
