Help with History's Rise and Fall of the Roman Empire?

There were several reasons the barbarian invasions weakened the borders of the Empire but this was also partly because the Empire's borders had become so large it was difficult to find enough of an army to defend such a large area The barbarians came to settle because they had been forced from their own lands by other tribes and they were very fierce fighters This combination of problems weakened the Empire to start with. Then in order to defense Rome and the Empire's borders the Emperors started paying settled barbarians to defend them from others - this created a drain on funds and the barbarians got a taste for Roman life and an idea of the power that could be held by the Emperor so their demands for land in Italy itself became demanding enough that they were given lands and then eventually took Rome itself to become the Emperor. There is a suggestion that there was a plague and/or famines that weakened the Empire as well at this time - possibly all due to climate change ! - a lesson for us today perhaps ? I also think - but check this out - the traditional farming cl of Italy drifted towards the cities so that there was less food production as the upper cles retired to the country increasingly and took previously good farming land for estates. Try BBC website, British Museum, Italian websites on ancient Rome.