That happened back in 683 and 716-717, and the Muslim invasion failed both times.
The current outlook for the Roman Empire for 1019 is quite positive. Earlier this year, Bulgaria was finally subdued. Although the powerful Fatamid Caliphate currently poses the main threat to the empire, relations between Constantinople and Cairo have improved and should expect to remain cordial for the time being.
To the east, the once-powerful Abbasid Caliphate, headquartered in Baghdad, has weakened considerably, but a new group in the region, the Seljuq Turks, is on the rise and should be seen as a major potential threat down the road.
Thanks. Sometimes I miss history by a few hundred years.
Heck, I hope I remember what I had for breakfast...
5.56mm