Formal embassies were an aspect of public life which continued from the later Roman empire through the fifth and sixth centuries into the time of the early medieval kingdoms. Originating in the exchanges of civitates before the rise of Roman hegemony, the ‘internal diplomacy’ of embassies played a fundamental part in the administration of the Roman empire. Cities, provincial councils, and other bodies communicated directly with the emperor and his senior magistrates, raising and resolving issues outside those addressed by bureaucratic administration, and maintaining the political cohesion of the vast empire through regular affirmations of loyalty. The conventions of the Second Sophistic, which flourished in the first and second centuries AD with a resurgence in the newly Christian empire of the fourth century, formalised the rhetorical practices of embassies, while imperial legislation regulated their conduct in regard to access to imperial officials, obligations and recompense for envoys, and the provision of state facilities to assist the undertaking of the journeys involved. Municipal and provincial embassies were thus officially coopted into the machinery of government. This system of internal communication was important to the functioning not only of the empire as a whole, but also of local society, where the successful completion of the burden of undertaking legations brought social advantage through prestige and perhaps rewards from the emperor. The traffic in embassies was essentially oneway: embassies from cities and provinces approached the imperial centre and returned with the authority's reply. The central government did not regularly need to delegate emissaries to represent itself to its constituents in the same manner.
Communications between the imperial government and external forces occurred largely through military channels. Only rarely were the conventions of internal communications transplanted to outside environments. The use of Sophists as envoys to foreign powers, however, begins to be attested in fourth-century relations with Sassanian Persia. The acceptance of permanent confrontation with an equally powerful neighbour, and a shared Hellenistic heritage, made possible two partial shifts: in the