Exactly when the noh mask came into being is not entirely clear however it is believed that masks, and their names still used today, were developed from the mid to latter part of the Muromachi period (1392-1573). Previous to that time, the mask conventions were not entirely set and masks themselves had stronger religious connotations. It was during the Muromachi period that the religious significance of the masks began to wane and they took on more human characteristics. It is thought that as performers started to think more about the use of yūgen (mysterious beauty) and profundity, they felt they needed to hide the unattractive aspects of their own faces and concentrate on making the beauty of noh stronger.
Between the end of the Muromachi period and the modern age the art of making noh masks was established as a hereditary art with a long lineage. Two examples are the Deme family from Echizen (present day Fukui prefecture) and
Cited: [1] “Noh Theater”. Facts and Details. 5/25/2011 http://factsanddetails.com/japan.php?itemid=716&catid=20&subcatid=131 [2] “Origin of the Noh mask”. Introducing the world of Noh. 5/25/2011 http://www.the-noh.com/en/world/mask.html [3] [4] [5] [6]