Genesis 36:12

And Timna was concubine to Eliphaz, Esau's son, having probably been adopted for that purpose by Adah; and she bare to Eliphaz Amalek; these were the sons of Adah, Esau's wife. If this is the Amalek that was the ancestor of the Amalekites who afterward were such bitter enemies of the children of Israel, it was probably due to the fact that Amalek separated himself from his brethren at an early date and grew into an independent people, his descendants occupying the country immediately south of Canaan and spreading from there to the very boundaries of the Promised Land.