The objective of this study is to examine the purpose and meaning of portrayals of Muslims in the Thai traditional art and architecture of temples and palaces. The focus is on the Siamese concepts of Muslims and the features of Muslims that Siamese people in the past intended to communicate to Siamese society. The study deals with the concept and design of painting found in Thai traditional mural paintings. The findings reveal that the portrayals of Muslims in the mural paintings represent the symbolic meanings which can be traced according 4 chronicle stages as follows: 
1. The otherness of Muslims from afar in the late Ayutthaya. 
2. The trace of Islamic civilization in the end of Ayutthaya, the Thonburi and the Reigns of King Rama I-II. 
3. The multicultural guests in the Reigns of King Rama III-IV. 
4. Unity under the royal patronage in the Reigns of King Rama V-VI. 
The benefit of the research can be applied to enhance the good relationship and understanding among different cultures in Thai society.