What factors played a decisive role in the decline of Rome?

The following factors played a role in the decline of Rome: internal political instability; frequent uprisings; the invasion of the Huns; barbarian tribes. Thus, in the 4-5th century, the Western Roman Empire entered the last stage of its existence. The last straw was the invasion of the Huns, after which Rome had no troops left to hold the borders of the state. Thus, the barbarians were able to easily divide and conquer the lands of the fallen empire.