Well, aside from the best known part of the world (the Province and the Free Cities), and the great unknown of whatever used to be in the Cath Bruig Empire before it was turned to a great swath of sand... there are the Twelve Duns, though I don't know if they would count as "civilized" given the Berserks' portrayal as stereotypical "barbarians". (Interesting factoid I just looked up: "dun" is an Indian word for "valley", specifically any river valley between the Himalayas and the smaller mountains at their feet). There's the Kingdom of Gower, though Myth 3 at least portrays that as being kin to the Twelve Duns culture (thus, maybe not civilized). There was apparently some kind of civilization on the Dire Marsh, since there are ruins near where the Watcher was killed.
Apart from human nations, the Dwarven cities fell, and I'm sure they count as "civilized".
Also, we don't know how unified the Province and the Cath Bruig were (either with each other or within themselves). The Cath Bruig Empire, being an empire, was necessarily composed of several nations. (That's the definition of an empire: a transnational state). The Province might likewise have been composed of several nations, in the strictest sense: bear in mind that the people of the British Isles consider themselves to be of at least four different nationalities (English, Scottish, Welsh, and Irish). For all we know the people around Covenant and the people around Tyr might consider themselves as different as Londoners and Dubliners, or even as different as English and Dutch (same distance, roughly). And I'm pretty sure we don't know that the Province was independent of the Cath Bruig; "province" most generally means "territory" and usually has implications of being under the control of a foreign/central power, so I always imagined them sort of "the frontier" of the Cath Bruig empire, who only became independent after the bulk of the empire crumbled.
