mabraham
Deity
I will call it "closed border teleportation".
When a unit is in foreign territory when borders are closed, they are "teleported" to the nearest neutral land territory. Once the land by Ning-hsia in Genghis' land is claimed as his territory, we can put a unit on the peninsula in Elizabeths land. We close the borders, and if there is an unoccupied land tile in the mountain island, the unit will be "teleported" there.
Clever.
I started an archer up that direction to consider trying that. We can also send our wandering chariot into Mansa's lands and try to teleport him to the island east of his lands.
This requires the AI to own all territory nearby. Potentially a stack can be teleported in if need be.
Hmm a whole stack sounds like a large investment for a doubtful outcome at an unknown time. If we have city vision to know when a Genghis border will pop, we'll have enough map vision to know whether there are any non-mountain tiles in that particular pocket.