I freely admit that I read both books at a speedy clip and will have to re-read to gain the subtleties...but my question is this: Is Alera a kingdom or a planet?
It is a realm that occupies the lion's share of a continent.

They share it with the Icement, who have been walled off a la China, only it's worked out a bit better, tactically, and done a little less damage to the economy. Alera, though, is the only nation of humans, and the word "human" and "Aleran" is essentially interchangeable.
The continent next door is linked to the one Alera is on via a land bridge which is where you find the Calderon Valley--hence its importance in relation to matters involving the Marat, who live next door.
The world itself is called Carna, but Alerans (like the inhabitants of many large and insular empires in our own history) in general don't spend much time thinking about things that happen beyond their borders.
Jim