From its very inception, the Sasanian political system encountered significant challenges in integrating peripheral regions into the ideological framework of "Ērānšahr". Iberia, as one of these regions, consistently remained a focal point of Sasanian assimilation efforts; however, its elites, drawing upon distinctive diacritical markers of identity, endeavored to delineate boundaries in order to safeguard their relative autonomy. The present research aims to identify the boundary-making strategies employed by the Iberian elites in response to the assimilationist policies of the Sasanians from 225 to 627 AD. The research questions are as follows: what soft and hard boundary-making strategies did the Sasanians employ to assimilate Iberia? And how, through the selection of diacritical markers of identity, did the Iberian elites redefine the boundaries of the 'in-group' against the 'out-groups'? The data for this study were gathered from library sources and examined through a descriptive-analytical method based on the theoretical framework of Fredrik Barth. The findings reveal that the Iberian elites, through deliberate shifts in religious markers from Manichaeism to Christianity and subsequently to Dyophysitism, gradually managed to overcome their identity crisis. By institutionalizing an independent church and the Dyophysite doctrine within the political system and popular beliefs, they succeeded in consolidating the boundaries of the 'in-group' against the 'out-groups'—namely, the Sasanians, the Romans, and the Armenians. In this process, the 'boundary' took precedence over 'content,' for while the religious content changed, the boundary between 'self' and 'other' was consistently reproduced.