Why did the Roman Empire fall?

1. Invasions by Barbarian tribes. The most straightforward theory for Western Rome's collapse pins the fall on a string of military losses sustained against outside forces. Rome had tangled with Germanic tribes for centuries, but by the 300s “barbarian” groups like the Goths had encroached beyond the Empire's borders.

Explanation: I think I have that right I’m not sure

which time period is this? or is this story fictional, i'm going to need more info to answer this question