I'm a historian of eastern Europe, I'm a specialist in this region.I've noticed that in general my colleagues avoid the larger tragedies that struck the lands we've studied, such as the Holocaust or Soviet Terror.Historians who write about the Holocaust usually focus on Germany, which is where the decisions were indeed made, but not where the killing took place. Meanwhile, historians of the Soviet Union usually don't notice that Stalin's killing policies were most lethal in the western Soviet Union.In other words, we are all researching the Bloodlands, but we have all failed to see the mass death as a single event at a given time and place.Each of the episodes I discuss in the book—Stalin's famines, Stalin's shooting campaigns, the joint German-Soviet occupation of Poland, the German starvation of Soviet POWs, the Holocaust—has its own story and its own historiography. But never before have they been brought together.Partly this is because few people know all of the necessary languages, partly this is because many fear to compare Nazi Germany and the Soviet Union.My own main purpose was not to compare, but rather to chronicle the individual killing policies of each regime.What I found was that the interactions between Nazi Germany and the Soviet Union were very often deadlier than anything one regime would have done on its own.The avoidance of comparison is a luxury in which we can indulge if we wish. The millions of Jews, Ukrainians, Poles, Belarusians, Russians and other Europeans touched by both regimes were condemned to compare.