It's rather small. Best solution to avoid having to paint ten billion principalties like in the HRE is to have de-centralized macro entities that you can refer to ("the Celts") instead of a billion tribes to keep track of (the Aedui, the Arverni, the Casse, the Belgae, ect.). To help offer a realistic sense of pre-modern pre-nation state decentralization, let's imagine a tiered system:
>Stage 1: Continental (European, Asian, Middle Eastern referring to West Asian and Egyptian).
For our template example - European.
>Stage 2: Regional (Iberian, Slavic, Germanic, Romance-Latins, Italians, Nordic, Semitic, Iranian in the ethnic sense from Azeris to Tajiks and Pashtuns). Modern day is your region or ethnic group.
For our template example - Italian.
>Stage 3: National or Pseudo-national (Persian, Median, Arab, Pashtuns, Franks, Visigoths, Ostrogoths, Aragonese, Portuguese, Dorian or Ionian Greek, Ghassanid or Lakhmid). Modern day is your country.
For our template example - Latin (at the time of the Roman republic)
Stage 4: Sub-national (Athenian, Spartan, tribal confederacies like the Ghassanids/Lakhmids, the Durrani and Ghilzai Pashtuns). Modern day is your region within a country, your state for us burgers.
For our template example - Roman (at the time of the Roman republic)
Stage 5: Tribal (the specific tribes, the city they belong to). Usually the city or county for modern day.
For our template example - Cornelia.
So we've got a character, Marcus Cornelius Avitus. He's a European, Italian, Latin, Roman of the Cornelia family.
You don't have to plan for all five for all your characters. Nor do you need all five for even a main character. Post limit so lemme continue.