What of the Thernonesians?

As powerful they seem internally they are deteriorating and suffering from imperial overstretch as is. Not to mention their armies are rather slow in speed due to all the supplies and logistics heaved onto their metaphorical and literal backs.

Also the relative isolation they have makes them shit traders despite having a merchant caste.

[quote=Dinh AaronMk]
And under these conditions I don't believe any high-energy foods could be grown. 
[/quote]

There's always making up a new crop that is fine with icey conditions.

Besides ice kingdoms are cool.