I have the same problem which only began when I purchased The Dead World DLC on steam last night. Previously using the steam package with the 3 DLCs both in 1.3 & 1.4 this bug did not appear. I can recreate this bug every time I play with the currently installed DLC. I would love to have a way to turn off or remove DLC packs; this would allow me to play the game while this bug is being hunted.
This is a screenshot showing the cloth map of my most recent game. http://i.imgur.com/6xunenX.jpg
This is a screenshot showing the extreme distance reached by the bug; it also took over my outpost. http://i.imgur.com/vlZNXC5.jpg
This is a screenshot showing the border encroaching on my kingdom. http://i.imgur.com/vRphM4j.jpg
I had to send out scout to even see the new border, which was not revealed. My Arcane Monolith which is extremely far away from the bugged kingdom was taken over by the border bug. When a city near a resource expanded it's border, it couldn't expand in that direction because the extremely distant foreign kingdom was building on the resource!
Thanks for your continues efforts to patch the game.