The Arm of Dorne was a land bridge that connected the continents of Westeros and Essos. It is now a cluster of islands known as the Stepstones.
History[]
Around 12,000 BC, the First Men crossed the Arm of Dorne from Essos to Westeros, supposedly under the leadership of High King Garth Greenhand. This migration lead to a series of wars between the First Men and the Westerosi natives, the giants and the Children of the Forest. The Children of the Forest used dark magic to raise the sea levels around the Arm of Dorne to halt the First Men migration, but it was already too late. The wars raged on until the Pact.