The question I'm asking is whether it is possible for the Abbasid revolution to stall once they took Mesopotamia, leading to a standoff between the Umayyads and Abbasids, one potentially lasting for decades or even centuries. I know little about this place and time in history, but from what I've read I have gathered that the Abbasid revolution was both very well prepared and had the support of pretty much everyone outside of the Syrian Arabs, so does that make Abbasid victory inevitable? Is it necessary that the Persians and Shia prop up an Alid rather than an Abbasid for this scenario to come to fruition?
Should the Ummayads hold on, how long until they can't sustain their momentum? Their state seems to have been running on loot, if the Romans and Franks hold and the east is closed off to them, do they head towards Nubia and Axum (why didn't they IOTL?) or do they simply implode? Is a reform or a coup by a more moderste clan the likelier option or do they get mopped up by whomever holds Persia? Thank you in advance for any answers.
Should the Ummayads hold on, how long until they can't sustain their momentum? Their state seems to have been running on loot, if the Romans and Franks hold and the east is closed off to them, do they head towards Nubia and Axum (why didn't they IOTL?) or do they simply implode? Is a reform or a coup by a more moderste clan the likelier option or do they get mopped up by whomever holds Persia? Thank you in advance for any answers.