What event is considered to be the beginning of the Middle Ages?

The event that led to the beginning of the Middle Ages is considered to be the collapse of the Western Roman Empire in 476 AD.
Due to the fact that a large number of Barbarian states were formed on the territory of the countries of modern Europe, which arose due to the Great Migration of Nations, in the European part of the mainland there was no single power concentrated in the hands of one ruler.
As a result, a period of stagnation in the development of society began, since almost all tribes began to wage active military operations among themselves in order to obtain absolute power on the continent.