reason behind the breakup of the caliphate and rise of sultanate?

plz check in the history book, from pg 86 to 87

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The downfall of the Abbasid dynasty led the way for the rise of the concept of the sultanate. The causes responsible were: 1.the successors of al mamum were very weak and incapable. 2.they paid no heed towards the administration affairs, 3.the caliphs paid no attention towards army. 4.they were leading a life full of luxury and paind no interest on the problems of common people.

It was like a piece of glass that's why

Hope this is helpful to you...