The subjugation of barbarian envoys in front of Theodosius I, as depicted in the Constantnople's obelisk in 390, soon turned out to be hollow. The same barbarians later became embroiled in a series of conflicts that would seriously undermine the stability of the empire and eventually produce a very different balance of power between the empire and its neighbours. This chapter traces this changing balance of power in late antiquity and its ramifications for imperial international relations. After 378, the balance of power shifted in favour of Rome's enemies, as the Roman Empire was consistently on the retreat with any territorial expansion. The substantial geopolitical transformations experienced by the Empire between Diocletian and the Arab conquest affected its perspectives both in terms of the ideological underpinnings that guided policy and the goals it sought to achieve through diplomacy. The late Empire relied on a fluid decision-making process that meant the implementation of foreign policy was rarely consistent.