Broken Arm
From A Wiki of Ice and Fire
The Broken Arm, also known as the Broken Arm of Dorne is the name given to the south eastern tip of Dornish peninsula, where the coastline breaks apart into a number of islands known as the Stepstones.[1]
According to legend, the 'Broken Arm', is where the land-bridge connecting Westeros and Essos was linked, before it was shattered by the Children of the Forest.