Please explain this art

[hi19hi19]

I was looking for epic fantasy landscape wallpapers, and I came across this inspiring, AVATAR-esque scene.

My question is, how the hell does one make a picture like this? The foliage on the lower left looks so real, that I feel like it might be photo-manipulation (espeically because it doesn't blend with the cliff face seamlessly, which is something I notice happens even in the best edited photos) But then again some parts look like they could be digitally painted, and other parts look like they could be 3D models.

What kind of software/techniques do you guys think went into a picture like this? Please explain, I am curious