Mar, one of the ancient divisions or provinces of Scotland, comprised the larger portion of Aberdeenshire, extending from north of the Don southward to the Mounth. Like other such districts, it was under the rule of a mormaer during Celtic times. In the 12th century an earl (the Earl of Mar) took his place, but no definite succession of earls appears till the 13th century, nor is any connection established between them and the mormaers.
Original text from the 1911 Encyclopaedia Britannica
