What document confirmed the feudal fragmentation of Germany?

From the moment of the formation of the Holy Roman Empire, a gradual feudal fragmentation began: part of the land passed into church possessions, many noble families acquired large land plots, splitting them into even smaller ones, but having strong power in them, Free Cities were formed.

The imperial power was weakened due to the uprisings of disgruntled princes of the empire and large feudal lords with campaigns of conquest in Italy, which they did not need.

Ferdal fragmentation was reinforced by the Golden Bull.