Uncharted Territory on a Map

[metricmodulation]

So, I am brand new to using photoshop to make a map. I am dabbling in a fantasy novel, and this is the world setting. My intent is for the Eastern areas to have not yet been mapped or charted by anyone in the culture of the story narrative, yet, much like settlements moving Westward during the American expansion westward. Lots of frontier area that isn't discovered yet, and sometimes no clue as to how far the land goes, or to what lands they are.

I am looking for constructive criticism, always, but I have a specific request:

How would YOU recommend I create the fog of undiscovered land/represent land being completely unexplored by anyone (in the culture who is expanding Eastward, at least)? I have a terrible cloud over the unknown lands, but there must be something far more stylish than what I've done.

First time map, so plenty of sloppiness, for sure. All comments and recipes welcome!