Welcome to EB,
Aedui - Gauls
Arche Seleukeia - Seleucid empire
Arverni - other Gauls
Baktria - easternmost Hellenic empire, close to "india".
Casse - British tribe
Epirus - Western Makedonians, remember Phyrrus of Epirus?
Getai - Tracians and Dacians along those lines.
Hayasdan - Armenians
Karthadastim - Carthage
Koinon Hellenon - Hellenic League, Sparta, Athens, Rhodos and friends
Lusotannan - a somewhat celtesque Tribe in Portugal
Makedonia - Macedonia
Pahlava - Parthians(tho you start out as their even more nomadic Predecessors, the Parni
Pontos - mix of Greeks and "persians" living in northern Turky
Ptolemaioi - Greeks in Egypt^^
Romani - Romans
Sab'yn - A people living on the southern tip of Arabia, remember the queen of saba?
Saka Rauka - nomads also known as Sakans.
Sauromatae - nomads also known as Sarmatians
Sweboz - a germanic tribe also known as Suebi
That's roughly the faction list for starters. I skipped prefixes.
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