Khusrau II successfully campaigned against the Roman(Byzantine) Empire to the point where he besieged the city of Constantinople in 626.  However, the Roman Emperor Heraclius made a deal the devil (the Turks) and eventually drove the Persians out of Byzantine territory. Like other Sassanid kings before him, defeat meant deposition.  A palace revolt staged by a number of elite Persian families was successful and Khusrau was executed.  Weakened by the civil war that followed, his successor didn’t last long as within a decade Arab armies swept north and east and destroyed the Sassanid Empire.   A choice silver coin AU