How did the treaty of Westphalia lay the foundations of modern Europe?

The Treaty of Westphalia, signed in 1648, ended the Thirty Years' War and established principles of state sovereignty and non-interference in domestic affairs, which became foundational for modern international relations. It recognized the concept of territorial integrity and granted states the authority to govern themselves without external interference, laying the groundwork for the nation-state system. This shift promoted diplomatic engagement and coexistence among European powers, setting the stage for the modern political landscape in Europe.