Why were borders changed in Europe and the Middle East after World War 1 and what was a lasting impact of those changes?

After World War I, borders in Europe and the Middle East were redrawn primarily due to the collapse of empires, such as the Austro-Hungarian and Ottoman Empires, and the desire of victorious powers to reshape territories based on national self-determination and strategic interests. The Treaty of Versailles and other agreements created new nations and altered existing borders, often disregarding ethnic and cultural divisions. A lasting impact of these changes has been ongoing ethnic tensions, conflicts, and nationalist movements, particularly in regions like the Balkans and the Middle East, where arbitrary borders have contributed to instability and violence.