He is the chief victim mentioned by name of a major joint military expedition led by the Anglo-Norman William de Burgh and the three sons of the King of Thomond, Domnall Mór Ua Briain (died 1194), namely Muirchertach, Conchobar Ruad, and Donnchad Cairprech, into Desmond.
The Annals of Inisfallen report the events as follows:[1] AI1201.12: A mighty hosting this year in Desmumu by William and other foreigners, together with the royalty of all Mumu, i.e. including Muirchertach Ua Briain, Conchobar Ruad, and Donnchad Cairprech, and many others, and their plundering parties were sent against Múscraige Mittaine, and they committed great depredations.
The legate and the bishops of Munster came and made peace between Síol Briain and Clann Charthaigh and Ó Mathghamhna and William de Burgo.
Olaf is in all likelihood the leader of the Uí Chairpri-led alliance in 1200 against Domnall Mór na Curra Mac Carthaig, King of Desmond, reported in the Annals of Inisfallen: AI1200.9: Domnall Mac Carthaig brought a hosting into Uí Chairpri, and the Cairprig, Múscraige, Cenél Aeda, Bárraid Ruada, and Bárraid Óca assembled [against him].
AI1177.3: Great warfare this year between Tuadmumu and Desmumu, and from Luimnech to Corcach and from Clár Doire Mór to Cnoc Brénainn was laid waste, both church and lay property.