Which major historical event is traditionally credited by historians and political scientists with establishing the core legal principle of state sovereignty, thus fundamentally initiating the modern nation-state system?

💡 Explanation:

The treaties collectively known as the Peace of Westphalia, signed in 1648, ended the Thirty Years' War and established the framework for modern international relations. It codified the concept of state sovereignty, meaning each nation-state has exclusive, supreme political authority within its defined borders, free from external interference.