To anyone reading, let me get this out of the way before I start. A lot of people get very defensive about WWII and the immediate aftermath despite it ending nearly 75 years ago. The population transfers you're talking about happened shortly after. People still have strong opinions about what happened back then. Because of this, I feel the need to preface this with the fact that what I say is in no way politically fueled. Whatever opinion I do have of the Soviet Union (or any country that participated in the war for that matter) has no impact on how I will answer this question. I'm not here to criticize the Soviet Union and I don't have any sort of anti-communist agenda. I am also not a Soviet shill. However, it is an undeniable fact that the percentage of people killed in Poland and the Soviet Union was higher than in any other countries.

To the asker of this question, based on the way you asked your question I get the feeling that you either prescribe to some revisionist theories that are sympathetic to Nazi Germany, or have gotten some information from someone who does. The information your question is based on is actually incorrect. "Reverse lebensraum" on the Germans sounds like something you'd see on Stormfront lol. Since you're asking about this however, I'll assume that's not you, and that you want a genuine answer-- not something to confirm some pro-Nazi theories.

Now , let's answer your question. While the Soviet Union (and many other countries in the aftermath of WWII) did engage in population transfers, it was the Polish government that expelled the Germans living in the territory--not the Soviet Union. It was however directly enabled by the Soviets and the Soviets also annexed Kaliningrad.

Why would they do this when they are "abolishing races" as you say? In a variety of ways the Soviet Union's leadership was highly hypocritical. They were also often untrue to the communist rhetoric they espoused. This is the case for a lot of countries--especially one-party, authoritarian states. (Like the fact that the Nazi's are known for being extremely anti-Semitic but Jewish friends and family members of Nazi party officials were often left alone despite the ongoing Holocaust.)

Publicly, the leadership of the Soviet Union was anti-colonialist, anti imperialist and believed in self determination. The problem is that the Soviet Union was only against these things when it suited them. During the cold war the Soviets supported colonial independence movements across the world. Not because they thought that these countries deserved to be free from their colonial overlords, but because it weakened their enemies.

Another example is Central Asia and the Caucasus during the Soviet Union. They were part of the Soviet Union, but the entire Union was politically subservient to the Russian SSR and government was made up almost entirely by the Slavic (mainly Russian) citizens of the country. Large amounts of East Slavs immigrated to central Asia during the Soviet Union. Just like they had in the Russian Empire Even today there are millions of Russians and Ukrainians in Kazakhstan.

Despite being anti-nationalist and racist, the Soviet Union condemned the Crimean Tatars to exile in Central Asia. There are numerous instances of the Soviet Union targeting specific ethnic groups for deportation to the country's periphery regions like Central Asia and more commonly known, Siberia.

So yes, the Soviet Union was officially for "uniting the workers of the world" and were anti-racist--to some extent. Were they willing to do things that are contrary to this when it suited them? Absolutely and without a doubt.

There's also the fact that Poland was not the only country to expel it's German population. There were Germans throughout Central, Eastern, and Southern Europe. In Hungary and Czechoslovakia (other countries too) Germans were also expelled. And Germans were not the only people expelled from countries. Poles were actually expelled from the territory annexed by the Soviet Union and East Slavs were expelled from the remaining parts of Poland.

Since the Soviet Union annexed the Eastern half of Poland and were now in the Soviet sphere of influence and because Germany was the aggressor, and loser, of the war, Poland was given territory at Germany's expense.

Now as to why the Germans were expelled, it's pretty simple. It's not like this was the only population transfer going on at the time. Europe had just been through a war started by the Germans to reclaim German speaking areas. Eliminating those German Speaking areas made it less likely that Germany would start another world war and it had already started two of them. People weren't feeling very pro-German.

Also as far as the territories being "historically German" goes, it's not actually that simple. While Germans constituted the majority of the population in most of these areas, and had for some time, East Prussia was inhabited by West Slavs and Baltic Prussians in the middle ages. Pomerania, Silesia and other areas of eastern Germany were also historically Western Slavic (Kashubians still exist in Pomerania and Sorbs still live in parts of Germany.) Poland actually referred to these territories as the "reclaimed territories." The vast majority of the land had once been part of the Kingdom of Poland and Western Slavic speaking.

Now I'll quickly tackle everything independently for those who don't want to read this text wall

• Were Germans subject to a Genocide? According to a few scholars, yes. The majority of scholars consider the expulsion of Germans after the war ethnic cleansing however. There is a distinction. The Poles were not attempting to eradicate the German race. Just like the Russians weren't trying to eradicate the Poles and vice versa

• Kaliningrad was annexed to the Soviet Union for it's geopolitical importance to the Soviet Union and the German population was removed from the region. Like I said above, self determination of peoples is fine just as long as it doesn't interfere with Soviet Interests. As far as being this being "reverse lebensraum"? No it's not. What happened isn't great but it wasn't the targeted extermination of Germans in order to make room for the superior Russian race. Königsberg was just useful to the Russians and if they didn't annex it the Polish most likely would have.

• The Allies had just fought a war against the Germans and the Germans had no will to fight. The population transfers removed the Germans from all of these areas. Concern about the agitation of Germans wasn't really on the agenda

• Even if the international community did care there was little that could be done. There wouldn't have been a cold war if the western powers we powerful enough to have kept the Soviets from doing what it wanted for the most part.

• They didn't let Russians settle it because it was Poland, not Russia

• They were not committing genocide and weren't trying "reverse lebensraum." It wouldn't even make sense for them to if they did think that East Slavs were Übermensch. The Soviet Union had plenty of arable land lol. That's why the Germans wanted it. And while they did immigrate to Central Asia and treat the non Slavic minorities worse than others, the USSR wasn't out to create a genocidal Russian ethno-state.

If there are any questions, comments, or rebuttals I'd be glad to hear them. Otherwise I think that what I've written is sufficient.