The Abbasid Empire was a medieval Muslim Empire that was, at the time, one of the largest and most powerful political entities at the time.
It was known as the Abbasid Caliphate and initially had its capital in Kufa, then Baghdad and eventually Cairo. From its early base in the Hejaz, it quickly conquered Palestine, Egypt, all of North Africa and beyond. At its largest, the Empire strected from modern Spain in the West to Modern Pakistan in the East.
This expansion helped to bring millions of people within the Empire, giving rise to an increase in trade, a widely used currency and a sophisticated credit and banking system which could be used in every corner of the Empire.
The strength of the huge Empire lied on its large internal trading business as well as their import and export with China.