Roger of Wendover even went so far as to provide a death date for Cissa, that had previously been absent. The date he gave was 590, which, given that Cissa is supposed to have arrived in Britain in 477, means that he must have been at least 123 years old when he died. An emendation from "died in 590", to "died aged 90" would resolve this inconsistency. As Kirby & Williams observed, "t seems very unlikely that these annals in later medieval chronicles will provide a certain basis for historical reconstruction".