Fall of Roman empire

Actually, What ended the Roman Empire was illegal immigration from German tribes, in exchange for letting the German stay in Roman territory they took all of the males into their mercenary army to defend Rome ... after sometime, the mercenary soldiers was a larger percent of the army then the Roman soldier,,,,the roman emperor marries daughter of the goth leader to keep him in check, then the emperor had his German general executed because he was afraid of him usurping the throne, but then all the goths in both the east and west were angry at the Roman emperor for killing their brother... western goths refused to defend Rome...eastern goth were already in league with Attila, they saw a power vacuum left when western goth general was execute and decided it was their spoils now that Rome was not under the protection western goth leader who was executed... the problem was that Roman lands were becoming more and more German due to change of power,,,and they preferred to rule using small feudal states instead of Roman system... they liked Roman system...but they didn't know how to run it being from a society that was feudal In nature...so Europe goes to sleep until their governing system becomes more sophisticated. In a way, I suppose it could be something wrong with economy,,, they don't have enough taxes, therefore the Roman government hires foreigners instead of local romans for army,,, then army becomes only half loyal and switches sides easily with goths.. actually, it all sounds kind of familiar...like it's happened before..