economic activity

Moreover, advancements in communication, such as an effective postal service, made record keeping, tax collection
The Abbasids were known for their vast trading networks
Key to the Abbasid's success was their exploitation of paper as a vehicle for efficient record keeping and control
The late ninth-century caliphate had economic problems & reduced the flow of tax revenue.
Maintaining networks of trade and communication was a challenge, though the Abbasids made strides, developing an extensive postal network