 Since the Gilaks are obviously out of place among these easterners, and as we know that Shapur I had to fight the Medes of the Mountains first before marching to the land of the Kushans, it is conceivable those Gilaks were the descendants of warriors captured during Shapur I's North-western campaign, forcibly drafted into the Sasanian army, and settled as a hereditary garrison in Merv, Nishapur, or Zrang after the conclusion of Shapur's north-eastern campaign, the usual Sasanian practise with prisoners of war.Ardashir I had, towards the end of his reign, renewed the war against the Roman Empire, and Shapur I had conquered the Mesopotamian fortresses Nisibis and Carrhae and had advanced into Syria.In 242, the Romans under the father-in-law of their child-emperor Gordian III set out against the Sasanians with "a huge army and great quantity of gold," (according to a Sasanian rock relief) and wintered in Antioch, while Shapur was occupied with subduing Gilan, Khorasan, and Sistan.