Zone Transition?

[syntaxlies]

Since the issue is really only present between Thanalan and Black Shroud, the easiest way I can think to address the issue (but not the best by any means) is to separate both areas by a huge mountain range that would occlude both regions from each other. Then the transition could simply be a tunnel through the mountain.

It's easier to imagine desert and rain forest on opposite sides on a mountain.

wow, this is exactly what i was gonna say.

edit: also a passage through giant whole in some sort of magical giant tree would be cool.(like that tree from avatar, but with a big whole in it)