Iberia became a tributary of the Sasanian state during the reign of Shapur I (241-272). Relations between the two countries seem to have been friendly at first, as Iberia cooperated in Persian campaigns against Rome, and the Iberian king Amazasp III (260-265) was listed as a high dignitary of the Sasanian realm, not a vassal who had been subdued by force of arms. But the aggressive tendencies of the Sasanians were evident in their propagation of Zoroastrianism, which was probably established in Iberia between the 260s and 290s.