The attacks on the Jews were witnessed by Ekkehard of Aura and Albert of Aix; among the Jewish communities, the main contemporary witnesses were the Mainz Anonymous, Eliezer ben Nathan, and Solomon bar Simson.
Napadi so morda izvirali iz prepričanja, da so Judje, enako kot muslimani, Kristusovi sovražniki, sovražnike pa je treba potolči ali pokristjaniti.