I've often seen the Sheiks of Praha and the Emirs of Sjaelland, yes. But no less common than Counts of Mecca and Dukes of Algiers or Baghdad, and if any game ever ended with one of the two civilisations being completely extinguished, it's almost always mega-Burgundy or something like that owning all of the East, hardly ever the other way.
I know what you mean. By 1300 most of the known world in my games pay tithes to Rome and Spanish is more commonly spoken in Mecca and Damascus than Arabic.