dreamscape: A dreamlike scene or picture having surreal qualities
This word is one of many which come from the word landscape. Landscape was originally used by Dutch painters to describe a new trend in art, to depict a section of countryside. Land =land/countryside + scape, meaning "the condition of".
So dreamscape is actually Dream + landscape. .many other words have been created using this idea: seascape, citycape, moonscape..it's a long list.