What are the preconditions for the fall of the Roman Empire. And in which the fall of the Roman Empire took place.

The main prerequisites for the fall of the mighty Roman Empire were:

Internal political struggle;
Lack of a strong leader who was able to take the empire into his own hands;
Constant clashes on the borders with barbarians;
Hunnic invasion.

Thus, in the 5th century AD, the Western Roman Empire could not withstand the pressure and collapsed. Rome was taken by barbarians in 476. After that, barbarian kingdoms began to emerge on the ruins of the empire.