Byzantine Judaism is one of the most unjustly neglected chapters in the history of Judaism. Most histories of the Jews barely mention Byzantium, and treat it as marginal. In fact Byzantium occupies the centre of the medieval Jewish world, and is in important ways the hub that links together the better-known regions (Iraq, Egypt, Italy, Germany and others). Judaism, which had very old roots in the Roman empire, was challenged and enriched by the encounter with Christianity. Most histories of Byzantium likewise ignore the Jewish dimension and focus exclusively on the Orthodox Church, ignoring the fact that Christianity grew out of Judaism and continued to be nourished by it.