The Treaty of Abernethy was signed at the Scottish village of Abernethy in 1072 by King Malcolm III of Scotland and by William of Normandy.
William had started his conquest of England when he and his army landed in Sussex, defeating and killing English King Harold Godwinson at the Battle of Hastings, in 1066.
William's army had to suppress many rebellions to secure the kingdom. As a result of the unrest, some English nobles had sought sanctuary in Scotland at the court of Malcolm III. One of them was Edgar Ætheling, a member of the House of Wessex who was the last English claimant to the throne of England.
Faced with a hostile Scotland, allied disaffected English lords including Edgar, William rode north and signed with Malcolm the Treaty of Abernethy. Although the specific details of the treaty are lost in history, it is known that in return for swearing allegiance to William, Malcolm was given estates in Cumbria, and Ætheling was banned from the Scottish court.