Thanks much all you guys!
@ Bookowl: I used some shaded relief art of our real world made by the CIA for the mountains and the relief, playing with several blending modes, hue, saturation and colors to match what I wanted to do.
@ Christie: due to the very high level of water evaporation, maintaining vegetation around rivers is also because irrigation systems that people set up there so it zlso depends on level of human settlements.
@ Vorropohaiah: yes rivers labels are kind of illegible at 50% size. I'll show some zoomed in area at 100% to check if it's ok. The broken line on the waveline was just made with a soft round eraser. And scale is planned btw I did have put a scale bar on my last maps, at least Selvarin, Kerngard and Lorn (not sure about Green Havens)
@Diamond and Eilathen: I'll may map larger map including the Sultanate one day but I would have to do several maps and then put them together since my computer won't handle such a big size in one file. By the way Sherassan was just intented to be a re-try and a practice map using the shaded relief at the start :p