One of the main sources for the lives and times of these jarls is the "Orkneyinga saga", which has been described as having "no parallel in the social and literary record of Scotland". One of the key events of the saga is the "martyrdom" of Jarl Magnus Erlendsson, later Saint Magnus, c. 1115. The last quarter of the saga is taken up with a lengthy tale of Jarl Rögnvald Kali Kolsson and Sweyn Asleifsson — indeed the oldest version ends with the latter's death in 1171.