Where the stormlands, the Reach, and the deserts of Dorne come together lies the harsh upland country the singers name the Dornish Marches, a land of poor stony soil and high windy hills, and for the greater part of recorded history it was the bloodiest border in all Westeros. The Storm Kings of House Durrandon claimed the Marches by right of the sword, as they claimed all the lands from the narrow sea to the edge of Dorne, while the Kings of the Reach of House Gardener claimed them as the western marches of the green realm sown by Garth Greenhand. Between these two ancient crowns the Marcher lands were fought over without cease, so that the maesters can no longer number the battles that were waged there, and the marcher houses of both realms grew hard and warlike from generations of raid and reprisal.
Neither House Durrandon nor House Gardener could ever hold the Marches long. A Storm King would carry his host west and take the border keeps, and a generation later a King of the Reach would win them back again, and so the boundary between the two kingdoms shifted back and forth across the hills for thousands of years like a tide that never sets. Nor were the two crowns the only powers to bleed there, for the Dornishmen beyond the Red Mountains raided the same lands, and the marchers learned to war on two fronts at once. The long quarrel was ended not by victory but by conquest, for when Aegon Targaryen came with his dragons the last Storm King, Argilac the Arrogant, and the last King of the Reach, Mern the Ninth Gardener, both perished in his fires; Argilac fell at the Last Storm and Mern upon the Field of Fire, and the Marches, with the realms that had fought over them for an age, passed under the rule of the Iron Throne.