This master is named for an altarpiece (early 14th century) of the Maestà in the Pinacoteca Comunale (below).   The art historian Mason Perkins first identified a body of works attributable to this master, who seems to have been a close follower of Duccio and possibly from Siena.  A number of other works that are attributed to him are illustrated in the website of the Fondazione Federico Zeri.  Most of these are in or from Siena. 

Città di Castello

Maestà (early 14th century)