At least three fragments places in Nikephoros Kallistos Xanthopoulos‘ narrative of the Avar wars have no parallels either in Theophylakt Simokatta or in Theophanes. The nature of the evidence cited in these passages cannot be a logical reconstruction based on the texts of either of the mentioned authors. This means that Xanthopoulos, the Church historian of the 14th century, had at his disposal a source on the 6th century which has not come down to us.
