Research of the Irano-Roman relations seems dominated by teh military perspective. This situation is cause by the very nature of the sources which mention both states mostly in light of the warfare waged between them. Equally fascinating are the diplomatic relations between Rome and Iran. One of the most interesting aspects of non-military relations are financial flows between both states. According to John Lydos, king Yazgerd was to
offer emperor Theodosius II (408-450) building together a fortress which was to block the passage through Caucasus. At the same time the king demanded from the emperor participation in the costs of the defense of the fortress. The problem of the reconciliation of the payments for defending of the Caucasian frontier became the grudge between the states making the rectification of the relationships even more difficult. The key problem seems to determine the peace negotiations which initiated Iranian claim towards the Empire. The second problem might be the motives which drove Iranian monarchs in their financial claims towards the emperors.