Euskal herria, 3 provincies: Vizcaya, Navarra and Labroud (The only provincies with basque culture)
País Vasco(Spanish)
euskal herria(Basque country)
When Spain collapse during the Great Collapse, the region to Basque country was unification the region to Basque culture and form the Republic of Euskal herria and preserved basque culture. Technology: Western
Culture: Basque
Ideas: Ideas to commerce, militar and expasion.
Religion : any you want.

That's a good idea, I'll probably add that today.

Cornish Commonwealth/Briton Union
-The provinces of Cornwall and two or three of the provinces in Brittany
-Major trade focus, defensive bonuses, 25% off trade ship costs maybe? Like a Venice, but on the English Channel
-Cornish/Briton culture

Northumbria
-Northumbria, Yorkshire, Cumbria, and Lancashire
-Combination of mild military and mild expansionist bonuses
-Anglican Religion ('cause why not?)
-Umbrian Culture

Southumbria
-The 3 provinces south of Northumbria that's not in Wales
-Combination of mild military and mild expansionist bonuses
-Anglican Religion
-Umbrian Culture

(Make the Umbrias more balanced than Korea :P )

Welsh-Irish Dependencies (WID)
-Wales and Ireland (Not Northern Ireland)
-More Trade/Naval ideas (What's with the Celts and trade?)
-Neo-Druidism Religion
-Welsh/Irish Culture

Ayreshire
-Ayreshire, Lothian, Ulster (Fife?)
-Defensive, Production Efficiency ideas, boost to force limit?
-Neo-Duridism Religion
-Scottish Culture

Canterbury
-Kent, Essex, 1 or 2 others nearby
-Religious Archbishopric (of course ;D )
-Anglican Religion
-Neo-English Culture

That's all I got ^_^

These seem like pretty good ideas, though I'll have to relay them to apljee since he's working on Brittania. I can also say with moderate certainty that the Salt Totemist religion will likely be in both the Iberian peninsula and the British Isles.

You should add a second Dutch union comprising of both The Netherlands and Flanders (Dutch-speaking part of Belgium). It's the Second one because the first one was of course formed around 1500.
Culture: Dutch, Flemish, Frisian
History: During the great collapse, the Benelux has faced many problems ultimately leading to its collapse. Around the 25th century, the northern part of the Netherlands (namely Fryslan, Utrecht and Gelderland) started to unite their survivors to become a powerhouse in the area. They started to expand south- and westward, but they noticed that it was still very dangerous around these areas, and with not much else to expand to, the Second Dutch Union decided to go defensive. This has helped them to survive quite a bit and made them have a significant advantage over other nations in defence.
Ideas: Mostly defensive ideas, but also cheaper tech and manpower
Religion: Based around their Reformed ancestors, but mostly up to you.
Capital: Somewhere in northern Netherlands.
Government Type: Any kind of republic could do.
You can of course shorten the name to SDU.

NOTES: This does mean that they have to take some territories from Rhine, and that's why I suggest having Rhine as an enemy of the SDU, to spice things up a bit in this region. Also, having the SDU have another religion than their Sunni neigbors, should make playing the SDU a bit higher level in difficulty, which is fun.

You should also try to make Paris more like a fallout region with a lot less development than the rest of France. Paris would then maybe be an uncolonized province with very aggressive and dangerous natives.

I like the Dutch idea, so I'll very likely add that. Thanks for the contribution! As for Paris, that has already been done. Paris's development is less than 10 and it's classified as a Ruined City.

Thanks! If you want, I could try to make some Second Dutch ideas.

Could you tell us which nations you already want to be added? That makes it easier for us to focus on which areas need adding. Like, if I wanted a nation in Calais, and you already have plans for Calais, then my idea will be a waste of time.

Yes, here are some excerpts from the 0.0.5 change log:

-Added Beaumont in Central France

-Added Euskal Herria, a Basque nation (Thanks Gaymer andrescortega)

-Added Diessenson in the Gascony area

- Added Lumiere in Paris

-(Not done yet) Add Second Dutch Union to the northern Netherlands area (Thanks Je Hooft)

Well, then I'll make that Calais-nation I was talking about!
Cales, owning the 4 provinces: Calais, Vlaanderen, Artois and Picardie.
Nation Adjective: Calesian
Culture: English, Kentish, Calaisien
History: During the Great Collapse, many people living in central and south England fleed either to Scotland, or the the European mainland. The Londoners and Kentish people especially fleed to Calais, where many would continue their journey. Even though many fleed further, some people stayed in Calais, where they made a living. Life was really harsh and it wasn't until the early 27th century that things started to improve. They established something called "Calaisien Rulership" where there was a dynasty that ruled for 40 years, and after that a new dynasty came. beginning 2630's, the Calesians started to engage a lot in trade with England. Years after they started to get a really high diplomatic reputation, and nowadays have a lot of allies.
Ideas: A bit of trade, a lot of diplo-related stuff.
Religion: Doesn't matter.
Capital: Calais
Government type: Calaisien Rulership, another dynasty every 40 years. Helps for diplo power. Fits in the monarchy type.
Tag: CLS

NOTES: I don't know what nations are going to be added in England, but it would be nice if they had some story to help relations between them and Cales.
Calais itself shouldn't have a really high development, just about as high as the surrounding provinces.

I like that idea, so I'm going to add that.

Iberica (Iberican; IBC)
Provinces of Aragon, Prineo, Cuenca, and Soria (Iberica Mountains)
Attrition, Fort Defense, Manpower Ideas
Vaultist

Okay, that sounds like a pretty cool idea. So you're talking about an Iberian vault society?

Well, why not? They'd be religiously different from those around them, yet still have the defensive ideas to keep them at bay, to an extent. Plus, nobody likes attacking across a river into mountains toward an 8 stack with defensive ideas and +10% infantry combat ability, for example.