The significance of the Treaty of Westphalia in ending the Thirty Years' War was its establishment of a new order in Europe based on the principles of sovereignty and non-interference in domestic affairs. Signed in 1648, the treaties concluded decades of religious and political conflict primarily involving Catholic and Protestant states. The agreements recognized the rights of individual states to govern themselves without external intervention, laying the groundwork for the modern nation-state system. The Treaty of Westphalia also marked a shift from religious to secular authority in international relations, fostering diplomacy and contributing to the balance of power that would shape Europe for centuries.