On the money with the scythian stuff only this word like tartaria confuses. Seems at different times it has been used to explain different things. A land mass, coalition of tribes, a race etc these so called "Germanic" defisntly brought a different order thats for sure. Before they sacked Rome there was many vandal and gothic battles against early christians of which they had an alternate version of called Arianism. Whats misunderstood as an invasion is actually many groups where invited to settle on roman lands and made up alot of legions. Some of these settled lands that where previously empty later became the holy roman empire. Although some may have been "barbarian" after this "invasion" things like knife an forks where used to eat and people starting wearing pants. Dosent seem like much of a fall to me.

Other notable things to imagine is the "Germanic" way of life was more about the individual, Rome was like a corporation. In Britain when the Anglo- saks (germanics) apeared the inhabitants where amazed to see each of them where adorned like a wealthy Roman as though each was a king. One story I've read is a meeting of British and saxons after a small group had landed. One of the new comers fills a bag with earth and sand and approaches the brit, how much do you want for this earth? The Brits confused by this but give a price, the newcomer agrees and pays them. They go back and think how are these rich men so stupid. Some time later they return to find the anglos have brought there families and settled and started building. It is then they realised they just sold the land to them and that they didn't even know they had owned.