The Abbasid caliphate is the biggest dominating power of the eastern Mediterranean and Middle East controlling the small remaining trade to India and The Shahnate of Persia as well as East Africa.
Its capital is Baghdad founded near Ctesiphon in the Persian-captured territory.
It's mostly Islamic due to the aggressive expansion of Islam from its predecessor Umayyad caliphate
Rise to powerThe Abbasids arose to power due to the continuous downfall of the Umayyads who had been losing terrain to the Romans and eventually to the Bulgars and that the Abbasid family gained power in the Shi'a dominated Persia. It was during the revolt of 757 when the Abbasids gained full control of the caliphate leaving only the hard lands of the Anatolian regions where many Umayyad family members hid and successfully survived the Abbasid persecution. They managed to form an army to fend them of Anatolia, they were as well helped by the fact of the secession of Egypt that wouldn't last too long
The biggest influence was and is the Umayyad caliphate which still has many followers in the Levant and Egypt.