That is an INCREDIBLY euro-centric viewpoint. Western Europe, at that.
Genocide and ethnic cleansing did not start or stop with Nazi Germany. Hell, by a lot of estimates, Imperial Japan killed more civilians during THEIR ethnic cleansing attempts.
And that ignores all the genocidal “Eastern European” wars of the 20th century, Russia’s actions, China’s ongoing horror, the hell that is Africa, and all the other wars. And that is just the 20th/21st century.