Later Arab tradition, as recorded by al-Tabari, considered the town a Sasanian foundation dating to Kavadh I (reigned 488–496, 498–531), but it is far more ancient: it was known since Assyrian times as Khalmanu, when it lay on the border between Babylonia and Media.

[1][2][3] According to Diodorus Siculus, the name derives from the settlement of Greek captives from Boeotia by Xerxes, who founded the town of Celonae or Kelonai (Κέλωναι).

[1][5] After another heavy defeat at the Battle of Jalula in 637, Yazdegerd left Hulwan for the eastern provinces of his realm,[6][7] and the town fell into the hands of the pursuing Arabs under Jarir ibn Abdallah Bajali in 640.

[8] In the early 640s, the town was of strategic importance as a frontier post between the Mesopotamian lowlands and the still Sasanian-controlled Iranian plateau, and was garrisoned by troops, including Persian defectors (the Khamra), who were settled there under the Rashidun caliphs.

[10] According to the 10th-century traveller Ibn Hawqal, the town was half the size of Dinavar, and its houses were built of both stone and bricks.