During the 20th century, national borders in Eastern Europe underwent drastic changes. By the end of the century, Eastern Europe looked radically different than it did in 1900. Contributing decisively to the border shifts were the two world wars, which concluded with massive geographical changes. This class will examine some of the most significant border changes over the past two centuries, focusing especially on Poland, Ukraine, and the Balkans. It will cover important geo-political impetuses and consequences. However, it will devote special attention to how the changes to national boundaries affected the people who lived in these regions, for many border changes came with massive population shifts (i.e., ethnic cleansing) and genocides.