The Treaty of Westphalia in 1648 marked the end of the Thirty Years' War and the Eighty Years' War, fundamentally reshaping the political landscape of Europe. The treaty established principles of state sovereignty and non-interference in the internal affairs of other states, thereby laying the groundwork for modern international relations. It recognized the independence of several countries, including the Netherlands and Switzerland, and altered territorial boundaries. The treaty is often cited as a pivotal moment in establishing the nation-state system, providing a framework that prioritized state sovereignty over religious affiliation and conflicts, significantly influencing subsequent European political thought.