In the books
In the A Song of Ice and Fire novels, Chroyane used to be the summer palace of the Rhoynar kingdom. Like most of the surrounding nation, it was destroyed by dragons unleashed by the Freehold of Valyria in its conquest of the area.
Chroyane today is a dreary ruin, frequently cloaked in mists. People infected with greyscale roam the area, essentially making the ruins a leper-colony. The sick are highly contagious and tend to gather in an area known as Bridge of Dream, which is a crossing of the Rhoyne near the southern tip of the Sorrows.