What is the significance of the Treaty of Westphalia in international relations?

The Treaty of Westphalia, concluded in 1648, is highly significant in international relations as it is often regarded as the foundational moment for the modern state system. This treaty ended the Thirty Years' War in Europe and established key principles that shaped the political landscape. One of the most important outcomes was the recognition of state sovereignty, which asserted that states have the authority to govern themselves without external interference. This concept became a cornerstone of international law and set the framework for how nations interact with one another.

Additionally, the Treaty of Westphalia marked the shift from a feudal system where loyalties were often divided among local lords and rulers to a system where unified, sovereign states held clear territorial boundaries and political power. This redefined relationships and interactions among nations, emphasizing diplomatic recognition and the importance of territorial integrity, principles that continue to dominate international relations today.

In contrast, the other options pertain to aspects that either emerged later or do not capture the primary impact of Westphalia. The principles of trade agreements developed over time and cannot be attributed to this treaty. Similarly, the League of Nations was established much later in the context of the aftermath of World War I, and while it was informed by evolving ideas of collective security, it is