The primary source on Christina is that of Icelander Sturla Þórðarson (Sturla was a nephew of Snorri Sturluson and had come to Norway in 1263). Sturla was commissioned by Kristina's brother, Magnus Lagabøter, (King Magnus VI of Norway) to write his father's saga ("Saga of Haakon Haakonsson ") shortly after King Haakon died in the Orkney Islands on 16 December 1263. In relating the stories in the saga, Sturla would have been able to interview contemporaries of the King and those that had taken the journey to Spain with Christina.