The Horims also dwelt in Seir beforetime; but the children of Esau succeeded them, when they had destroyed them from before them, and dwelt in their stead; as Israel did unto the land of his possession, which the LORD gave unto them.
The Horims lived in Seir long ago. Later, the descendants of Esau took their place after defeating them. Just like Israel took over the land given to them by God.