I suppose you're right, dominion does sound better in a completely different context. (Perhaps a scifi one or something not involving dominions)
*ponders*
I suppose Confederacy, Commonwealth, Empire, Caliphate, Emirate, Sultanate etc. are all fine substitutes (they can also go before, such as X of Acartharti.
Or simply Acartharsis.
Or 'Unified Acartharsis'.
Or 'Greater Acartharsis'.
Also, a play on the Mongols, The Silver Horde.
Also, a play on ancient China, The Four Kingdoms.
