Colonial Governor Gooch formally purchased the entire Shenandoah Valley from the Six Nations of the Iroquois by the Treaty of Lancaster in 1744. The Iroquois controlled the valley as a hunting ground. European settlement had already begun by that time. During Pontiac's War (1763–1766), Shawnee attacks reached as far east as the current county.
Shenandoah County was established in 1772. It was originally named Dunmore County for Virginia Governor John Murray, 4th Earl of Dunmore. Woodstock was the county seat. Dunmore was Virginia's last royal governor, and was forced from office during the American Revolution. During the war, in 1778 rebels renamed the county as Shenandoah.
Hardy County, West Virginia – northwest
Frederick County, Virginia – northeast
Warren County, Virginia – east
Page County, Virginia – southeast
Rockingham County, Virginia – southwest