Genesis 36:42 lists the kings who reigned in Edom before Israel had kings. This genealogy highlights the fulfillment of God's promise to Esau, Jacob's brother, that he would become a nation with rulers. It also serves as a historical record of the descendants of Esau, emphasizing the importance of lineage and the faithfulness of God in fulfilling His word. The mention of these kings in Edom sets the stage for the future interactions between the Edomites and the Israelites, showcasing God's sovereignty over nations and His faithfulness to His covenant promises.