From A Wiki of Ice and Fire
and the location of the Prince's Pass
The Prince's Pass is one of the principal overland routes from the Stormlands to Dorne. It is located in the Red Mountains of Dorne.
Its Dornish side is guarded from the castle Skyreach, the seat of House Fowler, which holds the title Warden of the Prince's Pass. The Prince's Pass descends from the mountains into the deep sands of Dorne. Structures along the route include Skyreach, Kingsgrave, and the Tower of Joy. North of the Prince's Pass is Nightsong in the Dornish Marches. Unlike the Boneway, the Prince's Pass does not appear to have a proper road.
The Three Leaves, three members of House Oakheart including Alester and Ser Olyvar, died in the Prince's Pass at the side of the Young Dragon, Daeron I Targaryen.
A Clash of Kings
Tyrion Lannister requests Doran Martell send his armies to the Prince's Pass to keep the marcher lords in their castles as part of the political betrothal of Myrcella Baratheon and Trystane Martell. Prince Doran Martell promises to move his banners into the high passes once Myrcella arrives safely at Sunspear.
The Winds of Winter
Two Dornish hosts have massed in the Boneway and the Prince's Pass. The hosts sit encamped, waiting for Prince Doran Martell to loose them on the enemies of House Martell.
References and Notes