arab invasion

Constans II was emperor of the Byzantine Empire from 641 to 668 arguably one of the harder times for the empire. As far as i am aware he tried to refocuse the empire on the mediterannean and atleast partly in the west and planned to retake italy. What if he was successfull with his plans, what...

With a POD after 610, your challenge is for the Byzantine Empire crumble before the Arab invasion while the Sassanid Empire, despite losing large swathes of territory, manages to hang on in its "heartland" (roughly modern-day Iran) and survive for a few more centuries. Bonus points if you manage...