Why did the Abbasids make changes to the Muslim empire?

The abbasid dynasty tried to make an empire founded on the equal opportunity of all Muslims. The new rulers stopped the large military subjugations, finishing the supremacy of the Arab military class. Under the early Abbasids, the domain of the caliphs touched its utmost prosperity and control and the Muslim civilization succeeded. Under the Abbasids, Islam turn out to be a more varied religious because discernment against non-Arab Muslims finished. The Abbasids also stimulated the capital from Damascus to Baghdad. This transfer into Persian land permitted Persian administrators to hold significant offices in the caliph's government.