The triangular format of the two panels suggests they originally formed the upper parts of a large altar polyptych, whose centre was occupied by the depiction of the Virgin and Child (now Palazzo Vecchio, Florence). The other parts of the retable were adorned with paintings of various saints - both male and female: collections worldwise show paintings representing St Catherine of Alexandria, St Margaret, and St John the Evangelist. Pietro Lorenzetti, along with Duccio and Simone Martini, ranked among the most important artists of the Sienese trecento painting. Pietro Lorenzetti with his brother Ambrogio supplied altarpieces and they also created frescoes (for example, they shared in the decoration of the famous basilica of St Francis in Assisi). However, their lives and painting work were prematurely finished by an epidemic of the plague, which struck Siena in 1348.