Ascension, you are correct that the mountains and trees are all brushes, but after a few smaller trial forests, I determined that it was too time consuming to place each tree with a brush. I tried different spacing’s and variables for the brushes themselves but they still looked too repeating, so instead if did created a pattern from my brushes.
Using the offset filter and a variation of the some twenty tree brushes I ended up with I created a fairly large pattern that I was unable to detect any perceivable pattern. Also, instead of simply pouring the pattern into the foreground, I actually created a new fill/adjustment layer with the pattern. That way I can actually change the size of the pattern at any time and simply paint in the trees where needed. This lends to far more flexibility than static layers. I could even change textures on the fly.
The mountain ranges were painted after the placement was determined. They are also brushes and were painted individually. I was unable to create an acceptable mountain range pattern and since there are considerably fewer mountains than trees, that was just fine by me.
A note about the font. The one I'm using is primarily is called Zothique Demo which is certainly difficult to read in many cases. That's why I'm also using one called "Treasure Map Deadhand" which is far more legible but still has many of the same overall characteristics. You can see a distinct difference at the bottom middle of the map. "The Horn of Avani" is in Zothique Demo while the "Sea of Minawara" is in Treasure Map Deadhand. I was reluctant to use two fonts, but Zothique Demo is just such a beautiful font when large enough to read I couldn't resist.
Nomadic, I can try to put together a brush pack at some point. I've got a whole slug of them at this point. Not all of them made the cut for the map. I went thru various styles of mountains before arriving at these. I modeled these after the ones used on the Ystraad map by Bohunk (which is most certainly the inspiration for this map.)
I've probably got some 120 brushes at this point made up. Of which only about a third are any good. When it comes right down to it, custom brushes are incredibly easy to make. What I've found especially effective is creating a 1 inch by 1 inch blank white canvas in photoshop with a resolution of 600 Pixels and drawing your trees, mountains, and other doodads with a brush between 3 and 13 pixels. When you shrink them down you can both cover your mistakes (as they are so small at that point) and also get a wonderful softness/crispness/detail balance.
Keep in mind that I now have over 35 mountain brushes made, but only used some 7 of them in the map. That means a LOT of trial and error.
Thanks again for the comments!