Basically, I think the new Haalkitaine/Rhakhaan book could use a listing of the various provinces (or whatever they are called in a feudal society)...
In medieval Europe the largest subdivisions (below kingdoms) were generally called duchies and counties. The duchies tended to be former kingdoms or important counties that were located in border regions, so their rulers got expanded independence and privileges. Technically a duke outranked a count, though in practice (and especially after centuries of private wars between nobles) some counts could overshadow some dukes if they were able to expand their holdings. In England, the closest analogues would be Earldom (like a duchy) and shire (like a county); in Germany, the word for duke was 'herzog', and the word for count was 'graf'.
The borders between 'feudal' principalities shifted constantly, so it would probably be a mistake to think of these as 'states' in the way the states in the USA have set boundaries. If the duke of New York State conquered Newark (New Jersey) from the count of New Jersey, he might incorporate it into an expanded New York State. People in the area might continue to think of Newark as part of the region of New Jersey, but for administrative and military purposes, Newark would now be a part of New York; and after centuries of that, people might even start to describe Newark in colloquial terms as part of New York. Similarly, in the Middle Ages, when Celtic invaders from Britain conquered parts of the old Roman region of Armorica, people started calling it 'Brittany'. And when Vikings conquered another part of it centuries later, people started calling it 'Northman-dy', or as we call it today, 'Normandy'.
The old Roman provincial names often survived, at least amongst academic writers. The church or course retained the Roman diocesan system, and it still had its provinces (the head of a church province was an archbishop). So you will find ecclesiastical writers for example still calling the area 'Armorica' even centuries after ordinary people had stopped calling it that.
