 Ever since the "humilating" Peace of Nisibis concluded between Shapur's grandfather Narseh and the Roman emperor Diocletian in 299, the borders between the two empires had changed largely in favor of the Romans, who in the treaty received a handful of provinces in Mesopotamia, changing the border from the Euphrates to the Tigris, close to the Sasanian capital of Ctesiphon.The Romans also received control over the kingdoms of Iberia and Armenia, and gained control over parts of upper Media in Iran proper.Shapur's primary objective was thus to nullify the treaty, which he spent much of his reign in order to accomplish.