Germany didn't ask the Russians for help as there was none needed. It was a strategical move on their part and the start of the dance which led later to the war at the eastern front..
What, give them a giant buffer zone before attacking it? Very strategic, indeed. This of course is the functioning of the genetically-superior think-tank Hitler put together. Signing a non-aggression pact so you can later stab a country in the back is for the lowly common folk...
real elites give them a bunch of land filled with people that hate and severely want to kill you between them and yourself and then declare war on their allies, first.
If it makes you feel better, nobody could have withstood the german army in 1940. They plowed through Europe like nothing before, the only thing what saved the Brits was the channel after they run with their tail between their legs.
It's what makes a lot of people feel better. That's the image most often portrayed of the German forces these days. It makes the French and British feel better for being cowards and unwilling to fight them until the last moment. It makes the Polish, and the rest of Europe, feel better for being overrun. It makes the Russians feel like straight-up heroes for being the point where reality (economy, resources, etc.) finally caught up with them. It makes the Germans feel better about themselves, and the Italians because they can technically claim to have helped.
Fact is, they had better technology and a whole lot more of it. No matter how many time-travel type fiction novels might disagree, the Nazis never really had any hope of winning the war at all. Just look what the US - having all the advantages of Germany at the time (economic, technological, population) did to you, and they didn't even begin with a fully mobilized military. That was back when it was an isolationist country unwilling to fight any other than minor nearby Hispanic countries unless directly provoked. And fighting on two fronts, too.
Well...the Belgians had Eben Emael - the strongest fort of the world, thought insurmountable - the French had a bigger and more modern army with more tanks than the Germans...did not help them one bit!
The Belgians had a fort, big deal. The French had... oh, come on. Like it matters what the French had. :)
Tell me why you totally circumnavigated Switzerland.
PS: You don't plow through Europe killing women and children, you know? It's abit counterproductive not concentrating your forces on the enemy armies...
It's what stopped the open assassinations of German officers and bombing of their buildings in Poland... wholesale massacre of the civilian population, that is. Though, to be fair, that's hardly representative of what the Germans did elsewhere... because what normal German would, at that time, want to be stationed in Poland? :)