by Elisa, Siviglia, Andalusia, 2000:
If I remember well, Moors' religion forbade them to represent their God and so they use complex geometrical design to worship him. This is a stucco in the Alcazaba of Siviglia.
Mudéjar is the name given to the Moors or Muslims of Al-Andalus who remained in Christian territory after the Reconquista but were not converted to Christianity. It also denotes a style of Iberian architecture and decoration, particularly of Aragon and Castile, of the 12th to 16th centuries, strongly influenced by Moorish taste and workmanship.
The word Mudéjar is a Medieval Spanish corruption of the Arabic word Mudajjan مدجن, meaning "domesticated", in a reference to the Muslims who have submitted to the rule of the Christian kings.
After the fall of Granada in January of 1492, Mudéjars kept their status for some time. However, they were forced to convert to Christianity in the mid 16th century, and were known as Moriscos from that time until those who refused to convert to Christianity were expelled in 1610. Their distinctive style is still evident in architecture as well as the music, art, and crafts of the region. (From Wikipedia)