Gregor Clegane is from the fictional kingdom of Essos.
The Duchies of Gwynedd are the largest feudal estates within the fictional Kingdom of Gwynedd in the Deryni novels of Katherine Kurtz . Ser Gregor Clegane , nicknamed The Mountain , is a fictional character in the A Song of Ice and Fire series of fantasy novels by American author George R. R. Martin , and its television adaptation Game of Thrones . Introduced in 1996 's A Game of Thrones , Gregor is the older brother of Sandor Clegane , from the fictional kingdom of Westeros .