In 1939 Nazi Germany and the Soviet Union signed an non aggresion pact (Molotov-Ribbentrop pact/German-Soviet non agreesion pact/Nazi-Soviet aggresion pact). This lasted from 1939 to 1941 when Germany invaded the Soviet Union (Operation Barbarossa).
This pact was meant to avoid conflict between the Germans and Soviets. Stalin apparantly trusted Hitler or thought he understood Hitler, and therefore believed that this would keep the peace between them.
In hindsight maybe Stalin should not be so comfortable with this agreement since Germany had earlier broken non aggresion pacts with multiple countries, among them Poland and Denmark. Hitler seem to have invaded pretty much all the countries he signed a non-aggression pact with. So it was more like Hitler will invade, but it will be postponed a bit.
But let's say that in an alternate timeline, Hitler does not declare war on the Soviet Union. What would happen? What would be the butterflies? The butterflies of butterflies?
If Hitler did not invade the Soviet Union would the Soviets also remain dedicated to the Molotoc-Ribbentrop pact? Would Stalin just use the time to build and prepare his own invasion?
Would Germany be better suited to fight against an invasion than to invade itself? Would Germany if invaded by the Soviets be able to later launch an counter invasion?
Would Germany in such a scenario eventually be able to force the British into an agreement?
How would the culture in Europe be affected by the absence of a Soviet German war?
Would the populations of occupied Europe become more compliant to German demands if Germany avoided this large war against the Soviets?
Links:
https://en.wikipedia.org/wiki/Molotov–Ribbentrop_Pact
https://www.google.no/search?q=hitl...AUICigB&biw=1517&bih=731#imgrc=xdm1zrO795A1PM:
https://www.cia.gov/library/center-...es/studies/vol50no1/9_BK_What_Stalin_Knew.htm