This chapter describes and discusses the material about the Sibyls as witnesses of Christ’s incarnation which circulated separately from the Sibylla Tiburtina during the Middle Ages. This material, which I call the Sibylline Tradition, 1 was pervasive in the medieval period and provided the context in which the Sibylla Tiburtina was understood. 2 Indeed, as later chapters show, the Sibylline Tradition often cross-fertilized directly with the interpretation of the Tiburtina. In other words, it steered medieval readers away from a political reading of the prophecy.