The guy on the far left of the photo has that "I'm going to get you for this " look.
From the three books I read (I gave up as I couldn't deal with the misery!) I got a Wars of the Roses vibe so would agree with the Captain and others suggesting that. The Scottish analogy probably isn't too far from the mark, with the wealthier families armed and armoured much like their southern counterparts. I seem to recall that there's still a lot of shield use in the books, which would be different from the period of likely influence (I can't remember if I remember that accurately from the books though!).
Some of the GoT TV costumes are all over the place with their apparent historic influences. For the most part I'm ok with it but some of it just looks awful (the Vivien Westwood jumpsuit attired Iron Men, for example). Still, if the BBC can have Vikings with big horned helmets on Doctor Who, I suppose anything goes (last Saturday's episode).
Edit: sorry, don't normally rant but those horns! Why! (apparently because people wouldn't have known they were vikings if they didn't have horns). Sorry, ranting again.