New Northumbria is basically England that thrives off of the tea industry and magical academy; they're small (ish, for the country) and don't have a strong military presence (assumedly because they have some kind of treaty or pact with someone to the east). What they lack in established military they made up in being pretty awesome on an education front, with one of the top wizarding schools in the world (in all forms of magical theory and practice that isn't unforgivable).
Magic that alters free will, kill, or torture is specifically forbidden to teach, and spells that intend to hard are taught for self-defense purposes. Necromancy is OK as it is in Equestria, assuming you have 'body rights' to practice Necromancy on. Interestingly, love potions are banned for manufacture given it affects free will.
Whenever a student or someone who has benefited from this learning is caught for breaking the law, they aren't killed but heavily obliviated and released to spare them their lives but wipe away any knowledge they can use irresponsibly.
It's assumed the sorcerers produced will do well enough protecting the country but it's never been really tested. More countries would rather learn from New Northumbria than attack it.
Normal people are treated well too; everyone knows magic exists and even if you're a muggle you have just as good opportunities in other studies. NN has a good rate of churning out smart educated people thanks to its again amazing education system.
Houndridge is the primer university on Terrestria for those without magical talent or capability, as you will learn everything there is to know about the world, world languages, specific regions, magical studies for muggles (to understand what magics each region has), geography, and all that good stuff.
I made this place up ages ago and was reminded of it when I reread one of the older threads the other night.