Okay, you know in the prophecy Unless the lost city will be found? Well, I think I know where it might be. I think that it is either JM (but that seems a little too obvious...) or.... between the ice and sand territories. The place where Blaze offered to Ice if she won as queen. I think this because it is flat, so moonlight could easily get to the eggs, and it is really no use to either the sand or ice because it is either too warm or too cold. Also, the sand territory is extremely large, expecially against the other kingdoms, so it probably wasn't always that large. That, but this seems a little far fetched, the city might be on a separate island all together. I mean, they were living on an island, so they might have found that island because their island sunk underwater, I don't know. Eh, comment your ideas in comments section.