The Aralor Empire and the lands to the north-west

[Gallien]

About the paper texture.
I used Adobe PS functions

1. I chose the main color - R 193 G 185 B 147 (you can change that of course).

2. Then I use the options of the Filter menu.

A) Filter/Texture/Texturiser
You need some texture to work with, something you will adjust later. There are 4 textures uploaded in PS by default (in my version) - brick, sandstone, canvas and sackcloth (I hope these are the right words, for I use the russian version). I used the sackcloth, but even the brick texture can be used, I think.
The only thing that matters now is the scaling and the relief. They define the final contrast of the paper, the size of grain.

B) Filter/Brush Strokes/Spatter
This step creates the texture itself. You have to adjust the spray radius and smoothness. The contrast of the result depends not only on these parametrs but also on the initial texture relief.

C) I blurred the result with Gausian blur (Filter/Blur/...). Later I thought that the texture is too blurred, so I went back to the Texturizer tool and used the Canvas texture with relief set to 1 (minimum). (You can compare the last map with the previous one.)

You can play with the settings on all the steps, depending on the size of the picture and on the contrast you want to have. You can also try to Spatter the texture twice for a more smooth paper texture. There are many different ways to use the PS Filter tools.

3. And the last point. I used 2 layers with black&white clouds. (Filter/Render/Clouds) (One layer for small-grained clouds and one for much bigger ones.) I set both layers to Multiply and turned the Opacity down to 5% or 10%.