Complex sentence: Haraldr was the son of Guðrøðr Rögnvaldsson, King of the Isles (d.1231), who was the son of Rögnvaldr Guðrøðarson, King of the Isles (d.1229).
Split into simpler sentences: Haraldr was the son of Guðrøðr Rögnvaldsson, King of the Isles (d.1231). Guðrøðr's father was Rögnvaldr Guðrøðarson, King of the Isles (d.1229).