I can't think of any realms being split in half in recent times. Back before the Big Update, when food had to physically move through regions, it was a legitimate tactic to cut a realm in half to starve some of the regions. I think that happened a few times to Fontan during the Sirion/Sultanate/Fontan war and they managed to hold the realm together to an extent. But I might be remembering it wrong since it was a few years ago now.
