Local factors have played an important role in the formation of settlements on earth and in the process of deciding on the forms, spatial arrangement and building materials of the structures within these settlements. While natural local data such as topography, geological structure, climate, vegetation and hydrological characteristics are effective in the formation of structures within the urban fabric, human factors such as socio-economic, historical and cultural factors are also determinant, independent of all these data. Religious buildings, unlike other types of structures, have been preserved for centuries under different civilizations due to the sacredness attributed to them and have been transferred to the present day. The rituals and worship order as actions taking place within religious structures can determine the spatial organization and spatial dimensions on the plan plane. However, in determining the construction, building material and building form of religious buildings, local construction techniques and knowledge, which are also influenced by previous civilizations, and the climate characteristics of that region create differences for the same building type. In other words, the desired physical comfort (such as temperature, humidity and air movement) within a building located in a certain region and the spiritual satisfaction based on historical and cultural events have brought out different building types in different geographies. Religious buildings are not built with the same typology all over the world, especially in order to provide a mystical atmosphere. The primary aim of this paper is to obtain a typology of traditional mosques in Western Indonesia that were formed under local conditions in the historical process and can also be used as an expression of early mosque architecture. This will be a reference for future new mosque designs and research, while on the other hand, it will enable us to discover local architectural values and understand how these characteristic features played a role in the construction of the society and local culture of that period. On the other hand, as a natural process of determining the typology, it is expected that the study to be carried out will also include the documentation activities of historical traditional mosque structures to a certain extent. Such a documentation study will also help to register and protect structures that have historical importance but have not yet been preserved and to transfer the cultural heritage to future generations. This study will also address the factors of adaptation to climate and geographical conditions that affect the development of mosque architectural design in Indonesia. It is hoped that the results of this research will provide a deeper understanding of the local influence on religious architecture and that the formal reflection and interpretation of spiritual expressions (rather than formal copying as is done today) can be a design data for modern mosques to be built in the future. It is expected that the notification will include explanations such as the elements that make up the plan layout of the mosques and the spiritual and local concept equivalents of the gradual transitions preferred in the roof form. This research, in which the spatial organization and form of traditional mosque architecture in Western Indonesia are determined by a typological analysis, will be carried out by grouping and classifying the mosque structural parts, taking into account their similarities and differences. Typological analysis of the selected mosques will be carried out in five sections as plan/spatial order, roof form, mihrab, decorations and the influence of local culture. Within the scope of the study, 5 early Islamic period mosque examples located in the Western region and having historical and socio-cultural values of the region will be studied. A region consisting of three main islands of Western Indonesia was determined as the research study area: (Java Sumatra and Kalimantan Islands). Within the scope of the study, it is considered to give examples of modern mosques designed by interpreting traditional mosques in Indonesia or other geographies with similar characteristics.