This document discusses the evolution of the international system from the pre-Westphalian era to the current neo-Westphalian system. It outlines the key characteristics of states and their sovereignty in the Westphalian system from 1648-1989, including the rise of nationalism, imperialism, and superpower rivalry during the Cold War. It then describes the neo-Westphalian system since 1990, noting the comparative rise of non-state actors through globalization and the relative weakening of exclusive state sovereignty in favor of a principle of responsible sovereignty.