Thanks for all the good comments guys!

So, I've been working on this for a while and I would like your opinion on a couple of things.

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1- The desert: I was not sure how to do it. There are sand dunes but they will probably not cover the whole desert areas. I'm still looking for a way to represent a dry area without using the sand dunes...
Anyway, for the part with sand, I'm not sure which of these is the best suited with the rest of the map (or if there is a better way to do it). Personally I like the one at the top right more but I was wondering if anyone had a better idea.

2- The farmland, I'm just experimenting for the moment. It looks pixelated and blurry at some place because I'm working with vectors.

3- The farm terrace: I think they are good but maybe they are too steep?

4- Not sure if it look odd but it's supposed to be a drier climate in altitude, so the trees are sparse and concentrated near the bottom of the valleys where there is plenty of water and the temperatures are warmer.

I also included the clouds even if I still don't know where I'm going to put them.