Eosin the Red said:
The WoT game is a great example of how to do this. It makes 3-4 skills "class skills" for anyone coming from a specific area. They also have regional feats - and the bonus human feat must come from one of the 4-5 regional feats that each region has access to.
I like regional feats. I also like favored classes. d20 Modern has a better system for adding class skills though. The problem with straight up assigning class skills is that it actually discourages people from playing the types of classes that should naturally come from an area.
Example:
The northmen are hardy survivalists, knowledgable in the secrets of nature.
ethnic class skills: Wilderness lore, knowledge (nature)
Okay, looks good? Well, the problem is that if someone plays a barbarian or ranger northman, they get no benefit from taking this ethnicity! Thus, you get most benefit as a northman from taking something else that doesn't already have these class skills, like rogue or fighter.
d20 Modern adds something extra to fix this problem. Before d20 Modern came out, I also independently arrived at roughly the same solution, which is how I can second guess the motivation. The fix is to say that if a character takes a class at first level that already has these skills as class skills, they gain a +1 competence bonus to them.
As a final note, the bonuses should be granted not based on ethnic heritage, but based on where the character spent his formative years. Thus, if a Zantaran grows up in the Northlands, adopted by a Northman family, he gets the Northman traits, not the Zantaran ones.
---Summary---
Ethnic groups have:
1. Favored class
2. The option to take cultural feats
3. Bonus class skills
4. For any bonus skill that is already a class skill at first level due to selected character class, a +1 competence bonus is gained.