Throughout the images created in the 13th and 14th centuries it is possible to discern a noticeable change in the depiction of Saracens. In the 13th century they are clearly depicted with almost no physical differences from Christians, and they must be differentiated through the use of equipment and heraldry. This might be an example of artists attempting to create a contemporary struggle for their audience to relate to, or perhaps it was a means of creating adequate enemies for the crusaders to battle.
Regardless of the reason, this seems to change in the later manuscripts from the 14th century. Throughout this period, in both the History of Outremer and the Grandes Chroniques de France, the depictions of Muslims become more and more focused on racial differences. Furthermore the depiction of Saracens begins to lean upon eastern headdresses such as turbans, and the variations, to depict Saracens. The topos for depicting Saracens that appears is then based almost entirely on dark skin and turbans.....
This blog quotes from the conclusions to "Bertrand, Benjamin Anthony, "Monstrous Muslims? Depicting Muslims in French Illuminated Manuscripts from 1200-1420" (2015). Honors Theses and Capstones. 236 to be found here.