Central Asia：
Turkic
Arab empire（ Rashidun Caliphate—— Umayyad Caliphate—— Abbasid Caliphate）
Persia（although it died in the early Middle Ages）
Fatimid Caliphate
Khwarazm
Seljuk
Kipchaks
Ghaznavids
Buyid dynasty
Rum
Xiliao
Zengid
Africa：
Ayyubid
Great Zimbabwe
East Asia：
Liao
Western Xia
Jurchen
Tibetan
Southeast Asia：
Siam
What do y’all think?
In addition, I think there should be a Crusader states,because the Crusaders are undoubtedly one of the symbols of the Middle Ages. 
What is the point of this thread?
As a digression, I dreamed that the developers announced in the live broadcast that they had begun voting to subdivide the buildings and soldier unit graphics of various ethnic groups.
I woke up happily and realized that it was a dream.
But they aren’t a CIVILIZATION.
I would strongly consider Mayapajit/Javanese
???
This post confuses me.
Also the list seems a bit too short