The words mostly refer to their history: the Martell's were the only ones that resisted the Targaryens, making them pretty much unique. They used guerilla tactics against the Targaryens, avoiding castles where dragons could get at them easily, avoiding clumping together in huge armies that could just get blasted by dragons, and they used the desert terrain to their advantage to harass invading armies. Being a desert, there was very little in the way of support for a huge invading army anyway, which is a problem for a conqueror and not so much a problem for those who live there.
I do love Game of Thrones, but I am disappointed in the fate of Loras Tyrell that is greatly different than was presented in the books. It seems the show has wanted to focus on Loras's sexuality, which is not how I remember the book in so much as he was the youngest Tyrell brother and had two older brothers who could step up and lead the house. In the television series, Loras is the only male heir to House Tyrell, which obviously increases the pressure because so much is bound to Loras's fate. Additionally, he attracts the eye of Jaime Lannister who becomes impressed with him, and he goes on to do some pretty great things before being maimed in a battle/seige at Dragonstone. As for Margaery, in the books she gets hauled before the faith because of issues having to do with being a virgin on her wedding night (there is doubt), but here she's just arrested because she's conspiring to deny charges of homosexuality leveled at her brother.
I think all of these deviations from the written material were necessary because 1) the volume of information that George R.R. Martin has written is simply too large for anything to handle (even a television series), and 2) the television series kind of "jumped the gun" and started filming while Martin was only halfway through the series. They really should have waited until the whole thing was commercially available for reading. That way they could prepare for all the different character arcs and make a proposal for more than seven seasons (allowing for deep exploration of the complex characters that inhabit Westeros).
Anyway, nothing's perfect I suppose, and as far as series go, "Game of Thrones" is one of the best fantasies I've ever had the pleasure to watch. So maybe I shouldn't be too critical. Just the whole "gay treatment" thing of a character as intriguing as Loras Tyrell kind of sticks in my craw.
But I do have a question for you writers out there. If a movie or television studio approached you to make your series into a show, would you consent if you were only halfway done? Or would you insist that they wait until the story is finalized? The answer is obvious for authors like J.K. Rowling and George R.R. Martin, but I'm interested if there are any of you out there that would play the "patience" card and insist that a film company wait until you were done. I look forward to your comments :).