If you want to expand human territory in the west, you should do so by working with Westgard. They have by far the strongest foothold, and even if you absolutely insist upon creating a new realm, putting it next to Westgard gives you the best chance of success.
(Of course, if you can't convince Westgard to actually support you, you're not much better off than if you'd just tossed your gold into the volcano.)
