Islamic Economics is a great webpage to learn the what, how and why of the Abbasids in an easy to understand and well sourced way.
it starts from the very beginning of the caliphates and gets you up to speed on the reasons for their revolution. if you want to know more of the Abbasids and who they were, how they viewed the world and their place in it as well as the basis for their economic and legal model its a good place to start. it has a mostly neutral point of view without much bias or wasting your time with fabricated drama and hyperbole like some clickbait YouTube video.
if anyone has a similar source of information for other civilizations I encourage you to share them. my own knowledge of the time periods Chinese and the Delhi sultanate essentially amount to “they existed”.