The Callahorn, also known as the Borderlands, is located north of Rainbow Lake, between the Irrybis Mountains and the Mountains of Runne. The region is home to several major cities.
The Callahorn is known as the Borderlands because of its position at the center of the Four Lands, separating the Northland from the Southland and the Westland from the Eastland. It is also called the Borderlands because of its committed resistance over the centuries to attempts by the Federation, the main governing body of the Southland, to annex the region.
Although residents of the Callahorn tend to be primarily of the Race of Man, the Borderlands' traditional role as a place for contact and commerce between people of all Races means that the makeup of the population is more mixed than in the Southland.
Individuals from the Callahorn are often addressed by outsiders as Borderman, Borderwoman, and so on.
- Tyrsis — The capital of the Callahorn and the largest city in the Borderlands. Tyrsis is a fortress-city. It has never fallen to any invading army, although its walls were breached once by the armies of the Warlock Lord due to acts of treachery. It is the home of the Border Legion, and also became the home of the Sword of Shannara following the Third War of the Races.
- Varfleet — A trading post. During the time of the Second War of the Races, Varfleet was just a small town. It was completely razed to the ground and everyone found was killed by the invading Northland army. Buildings were burned, people were killed, and animals slaughtered. After the war, the town was rebuilt. It is revealed in the First King of Shannara that Varfleet is Allanon's hometown.
- Kern — A city built on an island in the Mermidon River, with a citizenry that was a melting pot of the Races. Kinson Ravenlock and his wife Mareth settled the wooded island first, after the Second War of the Races. They farmed, then built a trading center and opened a supply route along the river. Other people from the Borderlands moved to join them on the island, and soon there was a thriving community. Centuries later, however, Kern is a deserted city, empty of everything except ruins.