A series of mountain ranges extending southwest to northeast and lying north of the Highland Boundary Fault and south of Strathspey, the Grampians rise to a height of 1309m (4296 feet) at Ben Macdui in the Cairngorm Mountains. They were formerly known as the Mounth, a name still preserved in the Cairn o' Mounth pass in Aberdeenshire and the plateau called the White Mounth to the south of the River Dee. The term Grampians was first applied by the Aberdeen historian Hector Boece in 1520 in reference to Mons Grampius, the site of Agricola's defeat of the Picts c.86 AD.