Culture groups map from EU4 wiki. Notice 4 monster groups in Asia/Africa, and mess in Europe.
Update a year later - most of these issues got fixed.
We need a serious talk because EU4 culture and culture group system is just awful. Just slightly blobby France can have 6 completely distinct culture groups (French, Iberian, Italian, German, Celtic, and Basque), but you can own all of Africa, half of Asia, and a pretty big chunk of Europe and fit all that in just 4 (African, Turko-Semitic, Altaic, and East Asian)?
Seriously EU4, pick one resolution and stick with it. There's no sensible interpretation under which it makes sense to put all of Africa or all of East Asia or everything from Crimea all the way to Kamchatka into a single group, but then make a ridiculous number of tiny groups for just about each European country.
There are two huge problems: 4 ridiculously large mega-culture-groups, and extreme proliferation of cultures in Europe.
Here's just one sensible proposal of globally meaningful, but you can pick up any scale and stick to it:
- India, Persia, and South-East Asia have very sensible granularity, and I'm extremely happy with it. This proposal is meant to give all heavily populated parts of the Old World similar granularity.
- Current Han/Cantonese should be one group without anything else - and divided into 5-10 different cultures, whichever way it makes most sense. I get it that China was far more culturally unified that India or Europe back then, but it was not this level of unified (just about any medium sized European country of that time has 2 cultures minimum), and that definitely did not extend all the way to Korea, and Japan.
- Speaking of which, Korea and Japan together would make a nice culture group, possibly with some minor nearby cultures like Manchu if it makes sense.
- African culture group really needs to be split, at a very minimum East and West Africa should be separate culture groups, since they're separated by massive wastelands, but there are probably great historical and gameplay reasons to add more.
- I understand why Arabic can be one huge culture group, but Turkish should not be part of it. Ottomans don't need any more gameplay help, and if they got on conquering spree, they'll probably accept most of that anyway.
- All of Altaic, Turkish, and Manchu need to be reassembled into some number of groups. It could follow basic geography of Middle East/Caucasus (Turkish, Tartar, Azerbaijani), North-East Asia (Manchu, Mongol, Siberian), and Central Asia (everything else), or something along these lines. Right now there are no major gameplay reasons to go one way or another since hordes are massively underpowered, and Ottomans will do well no matter what. Put Uralic in one of those groups as well.
- In a modest proposal all of France would be one culture. As is all of Italy. And all of Iberia. And all three together form one Latin culture group. Maybe, if there's a really good reason some of these three could be divided into 2-3, but not into silly minor cultures like Galician, Umbrian, and Gascon with just a couple of regions and status equal with Japanese somehow. That would be approximately right for 1444, and who knows how your history will continue from then on.
- Scandinavian looks really good. Byzantine looks reasonable. Germanic looks a bit overly divided into individual cultures, but it looks good as a group.
- 3 Slavic groups is a huge mess. There's no cultural basis for grouping Poles with Hungarians but separately from Ruthenians. Just group it into one big culture group, and kill any silly cultures like Schlesian (in 1444, seriously?), Serbian-vs-Croatian (the difference is primarily religion not culture), etc.
- British for English and Scots, but put Irish, and Welsh in the same group.
- Just throw Finnish/Estonian/etc. in Baltic group. It makes sense to have a special group here, not two special groups.
- That leaves Basque, and Briton unaccounted for. I'm tempted to just throw Briton into Latin group for long standing cultural ties reasons the same way Hungarians ended up fake Slavic. Basques can end up there as well, or as a separate weirdo group if there's a strong need to go this way.
- The New World is about fine as is.
- Much fewer culture union states. None is a valid number here, and with larger cultures most current culture union states won't have any legitimate reasons to have any.
This isn't just about cultural insensitivity - many aspects of gameplay like culture penalties, AE spread etc. are balanced for certain culture and culture group size, and are currently completely unbalanced depending on which part of the world you play in. Having roughly similar culture resolution - with exceptions for good historical (Chinese group will likely be big even when it loses Japan and Korea) or gameplay (Hungarians in Slavic group) reasons, not completely at random like now - will make for a much more balanced game, and it will allow more aspects of the game to depend on culture system, which currently is underutilized since it's too much of a mess to rely on it for anything.