An interesting guest
It would not require a genius to realize the value this realm held if it used to belong to the Crystal race - after all, they were the strongest race around. Furthermore, in the long history of the Crystal realm, it would be unrealistic to say that the Crystal race had never suffered any defeat, or given up any realms.
But, while suffering defeat was a possibility, it was much, much rarer for the Crystal race for several reasons. To fully explain the reasoning, a comparison between a settlement of the Crystal race and the human race can be made.