The border country, historically known as the Scottish Marches, is the area either side of the Anglo-Scottish border including parts of the modern council areas of Dumfries and Galloway and the Scottish Borders, and parts of the English counties of Cumbria and Northumberland. It is a hilly area, with the Scottish Southern Uplands to the north, and the Cheviot Hills forming the border between the two countries to the south. From the Norman conquest of England until the reign of James VI of Scotland, who in the course of his reign became James I of England while retaining the more northerly realm, border clashes were common and the monarchs of both countries relied on Scottish Earls of March and Lord Warden of the Marches to defend and control the frontier region.