I don't know – is it a bug or a feature, but:
Let's say, on a map fragment, there's water at the top and land at the bottom. Border gates are located on the border between the water and the land. And if a hero, after visiting a tent, disembarks through these gates from a ship onto land, then another hero can later board that ship and end up in the water beyond the gates. That is, they can pass through the gates without visiting the tent.
But this is a very rare case on the map, so you can just ignore it... :)
