Edomite Kings
Genesis 36:31-39

In Esau's list of descendants (Gen 36:9-43), Genesis 36:31 ("Now these are the kings who reigned in the land of Edom before any king reigned over the sons of Israel,") suggests the existence of an Israelite monarchy that has yet to occur hundreds of years later. And the following verses listed the names of Edomite kings who were born after Moses’ time.

Now these are the kings who reigned in the land of Edom before any king reigned over the sons of Israel. Bela the son of Beor reigned in Edom, and the name of his city was Dinhabah. Then Bela died, and Jobab the son of Zerah of Bozrah became king in his place. Then Jobab died, and Husham of the land of the Temanites became king in his place. Then Husham died, and Hadad the son of Bedad, who defeated Midian in the field of Moab, became king in his place; and the name of his city was Avith. Then Hadad died, and Samlah of Masrekah became king in his place. Then Samlah died, and Shaul of Rehoboth on the Euphrates River became king in his place. Then Shaul died, and Baal-hanan the son of Achbor became king in his place. Then Baal-hanan the son of Achbor died, and Hadar became king in his place; and the name of his city was Pau; and his wife's name was Mehetabel, the daughter of Matred, daughter of Mezahab. (Gen 36:31-39)

The first problem: did Moses know that there would be Hebrew kings when he wrote the Penteuch? It appears that Moses records the prophetic promises that God had made to Abraham, Jacob, and himself that explicitly mention Hebrew kings. God foretells that a Jewish monarchy will arise under two conditions: 1) when Israel is in the Promised Land, and 2) when the nation of Israel asks for a king.

Then God said to Abraham, "As for Sarai your wife, you shall not call her name Sarai, but Sarah shall be her name. "I will bless her, and indeed I will give you a son by her. Then I will bless her, and she shall be a mother of nations; kings of peoples will come from her." (Gen 17:15-16)

Then God appeared to Jacob again when he came from Paddan-aram, and He blessed him. God said to him, "Your name is Jacob; you shall no longer be called Jacob, but Israel shall be your name." Thus He called him Israel. God also said to him, "I am God Almighty; be fruitful and multiply; a nation and a company of nations shall come from you, and kings shall come forth from you. (Gen 35:9-11)

"When you enter the land which the LORD your God gives you, and you possess it and live in it, and you say, 'I will set a king over me like all the nations who are around me,' you shall surely set a king over you whom the LORD your God chooses, one from among your countrymen you shall set as king over yourselves; you may not put a foreigner over yourselves who is not your countryman. (Deut 17:14-15)

The second problem: the Edomite kings listed are kings that existed well after Moses.

Moses: 1527-1406 BC

The reign of Saul: 1020-1000 BC

The reign of David: 1000-961 BC

The reign of the 8 Edomite kings: 1152-995 BC

Despite Moses’ knowledge of the future of Israelite kings, many scholars are of the opinion that Genesis 36:31-39 was added to the genealogies of Esau sometime after Kings Saul or David and represents evidence of scribal gloss. One possibility for this insertion was to place a contextual perspective to the Edomites that Saul was fighting against and finally conquered by David. (1)

References:

1. Sarna N, Genesis, New York: Jewish Publication Society (1989), p.252.