How did the rise of nationalism influence the global community in the 20th century?

The rise of nationalism in the 20th century significantly reshaped the global community by fostering a sense of identity and self-determination among various ethnic and cultural groups, leading to the decolonization of many nations after World War II. This surge in nationalist sentiment often resulted in both the unification of countries and the emergence of new states, which sometimes sparked conflicts and civil wars. Additionally, nationalism contributed to the ideological divide during the Cold War, influencing international relations and alliances. Overall, it played a crucial role in redefining political boundaries and national identities worldwide.