I was going to try to it in Phantaria if we had been able to take over Chesney while Terran existed in the middle.
Also, D'Hara might have experience with this. Their realms is separated by water, not land, but same concept.
I think regions have to be touching your realm to take them over. That's why I was a bit worried with the concept of taking over Chesland and Chesney, because I assumed we'd need Gretchew first. Don't count me on that, though. And as for D'Hara, I believe sea connections count as touching. Don't count me on that either.