Thought has been seen as a common language behind the architecture of this land from the beginning, therefore, many experts have sought to explain and manifest a common language in architectural works. In each period of history, the development of new buildings can be witnessed maintaining the patterns of the previous periods while trying the continuity of thought in a more appropriate way than before. Meanwhile, religious complexes have the largest portion of the architecture of this land. This research aims to study the religious complexes of the 7th-9th centuries A.H. Tabriz city to clarify the thought and common language of Iranian Islamic architecture. The research is based on a compound method including historical interpretive and general descriptive-analytical strategy, and the obtained results indicate that Iranian-Islamic architecture is based on the continuity of thought, which can be seen as a common language and pattern in works derived from abstract, cultural, and social concepts.