In the history of Islamic landscape creating the fantastic open spaces cover a wide range of designs and techniques which consists of water systems and hydraulics, planting the exotic plants, sophisticated mechanical objects, zoomorphic spouts and fountains, ingenious garden devices, and decorative architecture. But creating the imaginary gardens should not be underestimated to the micro elements of the gardens. There were some spatial and organizational relationships between garden and geographical context, and also between open and closed spaces, in macro and middle scales, respectively. Considering the fact that many researches in the field of historical gardens in Iran are limited to the geographic region of Iran, the fantastic attributes and the mythology in gardens of Islamic civilization have not been much considered by Iranian scholars. Based on this gap in Persian literature the research questions are: what methods and elements of garden designing in Islamic civilization have been used to create a mythical and fantastic open space? Can we consider the environmental approach as the basic concept of creating the mythical and royal gardens in the early to the middle ages of Islamic civilization? This paper used an exploratory approach based on a descriptive-analytic research methodology, with a study of important English bibliographic sources for each garden. Furthermore, the researcher instead of obtaining a historiographical approach that examines the garden as an enclosed object, by adopting an environmental approach, considered the larger context from the perspective of study to discuss the causes and effects, and the balance between natural forces and cultural values. Garden sites that have the value of studying from the perspective of unique mythology represent the spectacle of the landscape architecture of the Islamic period, which includes a wide variety of gardens and landscapes which are geographically aligned with Muslim domains of governance from the second to the eleventh century. It means the author for completing this study has selected the garden sites from Spain, Maghreb, Algeria, Tunisia, Egypt, Turkey, Syria, Iraq, Iran, Central Asia, Pakistan and India. Based on the results of this study the author believe that the root of creation the mythical gardens in the Islamic civilization should be sought in the environmental approach of the landscape architects. The diversity of mythical gardens and mythological practices in the royal gardens showed the fluidity of the meaning of the garden and its placement on the frontier of imagination and reality. The lands conquered by Muslims who shaped the Islamic world (Saudi Arabia, Syria, Jordan, Anatolia plateau, Iran and North Africa) were largely desert landscapes that, as a result of irrigation techniques and agricultural growth in the Islamic period, the gardens were the symbol of sovereignty. It is important to note that the mythical gardens were not the result of extreme decorations, but the designers and gardeners of the Islamic period applied based on the three-dimensional environmental approach. In this model, emplacing the location of the gardens based on identifying the natural resources, either apparent resources (Andalusian, Ottoman or Mughal gardens) or hidden environmental capacities (Western Asian gardens) was the first step of garden landscaping in macro-scale. In the middle scale, landscape design and environmental features were affecting the audience. Thus, garden design, gardening practices and ornamental horticulture, and interaction between architecture and nature were being defined in middle scale. Eventually, the continuity of naturalist elements in landscape detail and decorative architecture could complete the innovative chain of creating a mythical open space.