"After Munich, IIRC this was no longer required"
And USSR was just taking back what was Russia's, and Germany was taking back what was Germany's. No more complaints about September 1939 from you.
And the Munich Agreement was signed on 29 (officially) or on 30 September in the morning (according to some sources). Regarding Zaolzie - according to the Munich Agreement, Zaolzie was part of territory which was allowed - by Great Britain - to be stolen by Nazi Germany from Czechoslovakia.
The Polish ultimatum to Czechoslavkia, was presented already AFTER Polish government was informed about the provisions of the Munich Agreement - including the provision of this Agreement, which granted part of Zaolzie (which was an area with majority of Polish population) to Germany:
"(...) On 30.09.1938 at 23:45 Polish government, after receiving information about provisions of the Munich Agreement, including the plan of handing over to III Reich areas which were considered as vital sphere of Polish interests (region of Bogumin), acting preemptively to thwart the German plan of taking this territory, presented a 12-hour ultimatum to Czechoslovakia, in which Poland demanded the return of inhabited by Polish majority Zaolzie (time to respond was until October 1st, 12:00, later prolonged at the request of Czechoslovakian government until 13:00). (...)"
And on 2 October 1939 Polish forces entered Zaolzie, in agreement with Czechoslvoakian government, which accepted the Polish demands.
So much regarding the alleged "cooperation" of Poland and Germany in "partitioning" Czechoslovakia - as our fellow ardent Communist forum members sometimes claimed in various threads (at the same time denying that there was ANY cooperation between Soviets and Germans over the partition of Poland in September 1939 - even though on August 23 an agreement and later on September 28 another agreement between Soviets and Germans regarding the division of Poland were signed, while in September / October 1938 Poland DID NOT sign any agreement with Germany over the alleged "partition" of Czechoslovakia).
I do not try to completely whitewash the Polish action - because it was still an example of a dastardly exploitation of situation in order to resolve an old territorial dispute (dating back to early 1920s, when Czechoslovakia - in an equally dastardly way, exploiting the Soviet offensive on Warsaw and hard situation of Poland - occupied the Polish part of Zaolzie), but I explain how incorrect are claims that Poland cooperated with Nazi Germany.
In fact, if Poland did not occupy this territory, it would have been occupied by Nazi Germany anyway.
There are more differences between Polish occupation of Zaolzie in 1938 and Soviet invasion of Eastern Poland in 1939, for example:
1a) The partition of Czechoslovakia was agreed and authorized (at Munich) by Western Powers, including Britain. And it was official.
1b) The partition of Poland was agreed and authorized only by the partitioners themselves. And it was kept as a secret.
2a) Czechoslovakia agreed on Polish ultimatum, thus Polish forces occupied the disputed area peacefully.
2b) Soviet Union presented no ultimatum. It invaded unexpectedly, without any warning, ultimatum, or declaration of war.
3a) Size of territory took by Poland from Czechoslovakia in October 1938 was 1,086 square km.
3b) Size of territory took by Soviet Union from Poland in September 1939 was 200,000 square km (or 184 times bigger).
4a) Poland - encouraged by Britain & France - refused to accept German demands, and was invaded. Later Soviets invaded from behind.
4b) Czechoslovakia succumbed to German demands, as Britain & France betrayed her and sold her to Hitler. Wehrmacht met no resistance.
5a) Soviet propaganda claimed that Eastern Poland - ethnically very mixed & diverse area - was "Western Belarus and Western Ukraine".
5b) Polish propaganda never called Zaolzie "Southern Poland" (even though ethnic Poles were clear majority of population there).
Etc., etc., etc.
Not even mentioning the whole complexity of political events between Poland & Czechoslovakia which took place prior to October 1938. As I probably already mentioned in some other thread on this forum - Poland was initially willing to help Czechoslovakia against Germany, in case of invasion. But Poland wanted to get back Zaolzie as a price for such help - but Czechoslovakia initially refused. Later it wanted to change her mind, but it was too late for Poland to discuss this again. So both sides loused up, and in both Poland and Czechoslovakia old disputes took the upper hand over fear of Germany's expansionism.
Both Poland and Czechoslovakia were victims of political games between Germany, Soviet Union, France and Britain.
And it is sad that both Polish & Czechoslovakian leaders were too blind to get over old territorial dispute, and unite against common dangers.
And USSR was just taking back what was Russia's
Oh, that would mean that only 1 of 15 countries of the Soviet Union had any interest in these lands (Russia was 1 of 15 countries of the USSR).
What a waste for the remaining 14 countries of the Soviet Union. And what an insult from you, to put " = " between Russia and Soviet Union.
BTW - did you know that 40% of Soviet soldiers who died in the Great Patriotic War, were not Russians ???
Probably not, since you are probably a Russophile. So I repeat this - Soviet Union was not Russia.
It included 15 countries, and even more nationalities and ethnicities. 40% of Red Army soldiers were not ethnic Russians. So Russia did not defeat Germany in WW2. Even on the Eastern Front. And number of Russian victims of WW2 must be reduced (or replaced by "Soviet victims of WW2").
Even your beloved Stalin was not ethnic Russian (and Stalin was not his real name). You see - everything you believe in, is just a fake.