Genesis 36:2
Esau took his wives of the daughters of Canaan; Adah the daughter of Elon the Hittite, and Aholibamah the daughter of Anah the daughter of Zibeon the Hivite; Esau took his wives of the daughters of Canaan; Adah the daughter of Elon the Hittite, and Aholibamah the daughter of Anah the daughter of Zibeon the Hivite;
Esau took his wives from the daughters of Canaan, Adah the daughter of Elon the Hittite, and Aholibamah the daughter of Anah the daughter of Zibeon the Hivite. The account of Esau and the nations that sprang from him comes after the death of Isaac at age 180 at Esau and Jacob's last meeting, when Jacob was about 109, Joseph was 17, and Benjamin was a small child two to four years old. The different names for Esau's wives in Genesis 26:34 are harmonized because the women and their fathers had other names: Adah was also called Basemath, Aholibamah was also called Judith, and Anah was also called Beeri. The term Hittite is used in a general sense that can include the Hivites, while this chapter gives the precise genealogy.
The Adah named here is not the same person as the Adah in Genesis 4:19. Reuse of a descriptive name in a later age does not make the person identical, just as the post-Flood Euphrates and Gihon are not the pre-Flood rivers of the same names. The Hittite ancestry in Esau's family line relates his descendants to the Amalekites, the enemies of Israel.