Carpathians

The Carpathians are a range of high mountains, stretching in a long arc through the heart of Europe. Even in the summer, they aren't easy to traverse. And in the winter, when snow blocks the mountain passes, the Carpathians become an insurmountable wall.

I guess that is why Brencis chose Vale Sangora to be his realm. When it comes to controlling borders, it's hard to think of a better place.