Adam and Eve had at least three sons, Cain, Abel, and Seth. Cain killed Abel of course and the Bible story after that concerns the third son. Before, however, that story is told, we are given insight to the lineage of Cain (chapter 4).
Noah had three sons, one of whom was cursed. The Bible story deals with his son Shem, but before that story is told, we are told of the descendants of the other two (chapter 10).
Abraham had numerous sons, but two stand out: Ishmael and Isaac. The Bible story deals with Isaac but before that story is told, we are given a look at the descendants of Ishmael (chapter 25).
Isaac had two sons, Jacob and Esau. The Bible story centers on Jacob with Genesis focusing mainly on Jacob’s son, Joseph. But before we are given his story, chapter 36 deals extensively with Esau’s descendants.
My point is that at every major turning point in the Genesis story, we have a look at some of the people who are going to be dropped from the story. Esau’s descendants are especially significant because they would prove to be some of Israel’s most persistent enemies – all the way to the destruction of Jerusalem in the sixth century B.C.
Altogether Esau had four wives, three of whom came from among the Canaanites and one from the line of Ishmael – both enemies of Israel. But other than to bring us up to date on the people about to be dropped, why might we have this extensive list in chapter 36?
Isaac did forsee that Esau would be the father of a powerful people. They do grow rich, but they cannot get along with their kinsmen (the reason for separating is akin to the reason for the separation of Abraham and Lot). They grow to displace and overcome the Horites living in the area of Seir. In that sense, they are more successful than their brethren Israel who are never able to totally displace the inhabitants of Canaan. Finally, they are led by a series of eight kings who are all great. The first name in the descendant list is “Eliphaz” whose name means “my god is fine gold.” The last one is “Mezahab” which means “gold water.” The writer may be pointing to the very materialistic nature of the Edomite kingdom, the legitimate heirs of a father who lived only in the moment and was willing to trade eternal treasure for something far less permanent.