In "The Return of Marco Polo's World," Robert D. Kaplan discusses the collapse of various Muslim prison-states, attributing their downfall to both internal factors and external interventions. This destabilization has resulted in significant refugee crises, overwhelming already struggling European economies and societies. The influx of refugees from these states poses challenges for European nations, which are grappling with their own economic difficulties.

Kaplan highlights the broader implications of these collapses on global politics and American interests in the twenty-first century. The movement of populations across borders not only affects local economies but also reshapes geopolitical dynamics. As Europe contends with the ramifications of these migrations, the interconnectedness of global stability and security becomes increasingly evident.