Two of the texts, B and C, begin with a World Chronicle derived from Isidore of Seville's "Origines" (Book V, ch. 39), through the medium of Bede's Chronica minora. B commences its annals with Julius Caesar's invasion of Britain "sixty years before the incarnation of the Lord." After A.D. 457, B agrees closely with A until A ends. C commences its annals after the empire of Heraclius (AD 610-41) at a year corresponding to AD 677. C mostly agrees with A until A ends, although it is clear that A was not the common source for B and C (Dumville 2002, p. xi). B and C diverge after 1203, C having fewer and briefer Welsh entries.