The first Robert de Brus, the ‘conquisitor of Cleveland, Hartness and Annandale’, founder of the Augustinian priory of Guisborough and progenitor of both the English and Scottish branches of the family, came into England from the west of Normandy among the followers of Henry I in or around the year 1100. By 1103, when he makes his first appearance in royal records, Robert had already acquired some or all of the estates which made up the core of his Yorkshire fief, comprising more than one hundred manors granted to him almost entirely from the royal demesne and land of the ‘king's thegns’. Within another fifteen years he was in possession of the rest of those lands in the north-east of England, and possibly also those in south-west Scotland, which would provide the basis of the family's power for the next two centuries. It was a rapid rise and, though not without precedent among those whom Henry favoured, suggests that Robert was a man of ability in whom the king had sufficient confidence to entrust him with such responsibility in a difficult region.

When Henry seized the throne in August 1100, the far north of England was still largely outside Norman administrative control. Despite the building of a strategic castle on the Tyne by Robert Curthose in 1080 and at Carlisle by William Rufus in 1092, and despite Rufus's establishment of loyal followers in southern Cumbria, his decisive quelling of Mowbray's rebellion in 1095, his subsequent abolition of the earldom of Northumbria and creation of a handful of lordships on the Tyne, royal authority in the region was far from secure.