This article explores what James Rosenau had founded as a post-international politics paradigm. It does so through a comparative reading of the two concepts of the two coexistent systems, state-centic and multicentric, on the one hand; and neomedievalism on the other. The article aimes at offering some reflections on the essential characteristics that both concepts can contribute to improving our understanding of post-international politics in an era of increasing complexity. The article is divided into two sections. The first section introduces the concept of post-international politics, from Rosenau's perspective, and identifies the most prominent assumptions on which Rosenau called turbulence (another label for the post-international politics paradigm). The second section introduces the concept of neomedievalism, which traces back to Hadley Bull, as an appropriate depiction for a system within which the state's monopoly of violence is constantly declining, especially under the growing influence of private armies/security companies, which are considered a contemporary example of the mercenary armies that characterized the first medieval period.