Complex sentence: There was no dominant potentate in Moray during 12th and 13th centuries and the bishops ruled their territories with a great deal of independence but this ended when King Robert I of Scotland elevated Thomas Randolph to the earldom of Moray sometime between 12 April and 29 October 1312.
Split into simpler sentences: There was no dominant potentate in Moray during 12th and 13th centuries and the bishops ruled their territories with a great deal of independence. This ended when King Robert I of Scotland elevated Thomas Randolph to the earldom of Moray sometime between 12 April and 29 October 1312.