Does European colonialism's role in eliminating indigenous leadership and kinship networks count? Or do you mean some kind of "internal" decline?

One of the great medieval works of political science, Ibn Khaldun's Muqaddimah describes exactly this. In his political theory tribal peoples living on the periphery develop and exhibit what he terms "Asabiyyah" which might well translate as sort of "tribal kinship". This kinship is the basis of their military might but upon taking power, within a matter of generations, this feeling of kinship or martial unity is diminished as the tribe adapts to a settled life of the luxury of imperial rule. They are then eventually usurped by a younger, more-virile tribe.

It remains an influential work in discussing the dynastic cycles of the Islamic world.