There was plenty of small Kurdish states in the eu timeline that were at times independent but mostly loyal to one overlord or another. A great number of Kurdish emirates switching sides is part of the reason the Ottoman can so quickly expand east into nominally Safavid lands in their early conflicts.
We have a few of these as playable countries, Bitlis, Ardalan, Hisn Kayfa (the map level of detail does not really allow for all that existed to be included however).
No United Kurdistan existed though and having separatists forming it due to pre existing cores would be wildly out of the era.
Still the geographic region was often referred to as Kurdistan (ie the lands were the Kurds live) throughout the era, so a unification tag would not be entirely out there. It would be a pretty small state though, as far as eu unifications go, so I’m not going to make any promises about that.
Achaemenid Persia is wildly out of the timeline however, and would be too old for crusader kings or even for that matter our earliest timeline game EU:Rome.
