People that knew what they were doing invested in the new economy and became wealthier.
YOU FOUND THE ANSWER TO LIFE?? And scientists said it was impossible T-T
When the Nazi's fled and the Russians (I believe) invaded was a huge turning point giving jews and all others captured, hope and freedom.
The Germanic tribes were much more culturally set back than the romans in things like buildings, writing, and art. The Germanic tribes were mainly nomadic so they never settled down to build magnificent buildings such as the Colosseum. The Romans at one point switched over to christian religion and the Germanic tribes were pagan, so after the Roman Empire collapsed, Christianity almost died out in most of Europe.
The fall of the Aztecs is due to their treatment of others and neighboring civilizations. Hope this helps :)