Members of the family occasionally used the toponymic surname "de Stauf" or variants thereof. Only in the 13th century does the name come to be applied to the family as a whole. Around 1215 a chronicler referred to the "emperors of Stauf". In 1247, the Emperor Frederick II himself referred to his family as the "domus Stoffensis" (Staufer house), but this was an isolated instance. Otto of Freising (d. 1158) associated the Staufer with the town of Waiblingen and around 1230 Burchard of Ursberg referred to the Staufer as of the "royal lineage of the Waiblingens" ("regia stirps Waiblingensium"). The exact connection between the family and Waiblingen is not clear, but as a name for the family it became very popular. The pro-imperial Ghibelline faction of the Italian civic rivalries of the 13th and 14th centuries derived its name from Waiblingen.