Having lived together on the Iberian Peninsula since the 8th century, Islamic, Christian, and Jewish communities all contributed to the birth of Mudejar architecture in the 11th century. This style, which appealed to members of all 3 religions, was generously applied following the re-conquest movements of the Christian kingdoms in the Iberian Peninsula when they sought to expel their Muslim enemies. Mudejar architecture is a problematic topic of architectural history writing. Studies that define Mudejar origins and character were mostly conducted by Spanish scholars. While one group of scholars explains that Mudejar origins have Islamic roots, another emphasizes its Christian aspects. Notably, recent research has altered former classifications, concentrating on geographical facts in addition to cultural varieties. This study investigates the sources of Mudejar architecture and draws attention to the origin, identity, and historiographical problems that are common in architectural history studies. An evaluation of historical writing about the Mudejar concept, particularly survey books, will help us to identify the ambiguities and clarify the conceptual and terminological tools used.