No, I’m not teasing you, but I think that is the answer. I’m not sure at what level the specific kingdoms unlock, but remember from my own experience that the kingdoms unlocked in a particular order from the center of the map outward. It’s been about 22 months since I was level 58, so my memory of things like that are foggy at best. I think you should still be able to see the kingdom even if it isn’t unlocked, though, so your next step might be to submit a support ticket to see if there is something that can be done, or give you a definitive answer about what you need to do to unlock the kingdom.
It seems a bit silly that they would have an important feature of the game locked in a kingdom that is only accessible by players over a certain level, but if I remember correctly, I had to wait until I had unlocked Zhul’Kari before I could play Treasure Hunt. Might be a similar thing here.
If you want to submit the support ticket, you can go here: http://www.505games.com/contact