In the course of his life, Duccio had many pupils even if it is not known if they were true pupils who were formed and matured artistically within his workshop, or they were simply painters who imitated his style. Many of the artists are anonymous, and their connection to Duccio has emerged only from analysis of a body of work with common stylistic traits. The first pupils, who can be referred to as a group as first-generation followers, were active between about 1290 and 1320 and include the Master of Badia a Isola, the Master of Città di Castello, the Aringhieri Master, the Master of the "Collazioni dei Santi Padri" and the Master of San Polo in Rosso.