In the world of dreams the rules of reality do not necessarily apply. Each dream is unique and it's a direct link to the soul and spirit. Psychology provides its own theories on what dreams mean, but so did tradition and the study of dreams for thousands of years before any relevant science had developed.
Dream Meanings - Valley
If you dream of a cultivated valley with trees, you will soon have success in matters that have been on your mind recently. However, if the valley is dry and treeless, then expect problems and delays in your affairs.