The were many reasons 1Invasions 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
2Economic troubles and overreliance on slave labor
Even as Rome was under attack from outside forces, it was also crumbling from within thanks to a severe financial crisis
3The rise of the Eastern Empire
The fate of Western Rome was partially sealed in the late third century, when the Emperor Diocletian divided the Empire into two halves—the Western Empire seated in the city of Milan, and the Eastern Empire in Byzantium, later known as Constantinople.
4Weakening of the Roman legions
For most of its history, Rome’s military was the envy of the ancient world.
there were a lot more reasons as well but these are the main ones hope I helped
