1/15- Russia and Germany

In class, we had watched a video that talked about Germany and its rise on becoming the strongest force on Earth.  Why had no one stopped them? Why couldn't all the other countries come together as one and beat Germany? France and Britain had cowered and stayed behind, not attempting to fight Germany as they had disobeyed the treaty of Versailles three times. Yes I understand that the U.S., France, and GB all had wanted peace, but Germany was slowly tearing apart Europe again and taking over countries.  My biggest question would have to be is why Russia, just as strong as Germany, not stopping Germany?  Russia  had its own problems and they must've felt that trying to fight Germany would have drained their country of their army.  Instead of fighting Germany, they signed a treaty with them declaring peace between the two for ten years.  Russia had been mostly passive before this, but they secretly made an agreement that the two countries could split Poland. Why did Russia want Poland, and what was Russia thinking this would do for them?  Russia was very strong but also very disadvantaged at times when it came to war in other countries (Finland Winter War).  Russia ended up fighting Germany in the end!  I am mostly confused that Russia did not become active until later in the war and why had they not attacked Germany sooner.