These are the kings who reigned in Edom before any king
reigned over the descendants of Israel.
Genesis 36:31
Although Esau’s descendants tried to establish an organized kingdom with a local, native monarchy, they never succeeded in doing so. The Torah informs us that the eight kings who ruled Edom were not Edomite kings; the Edomites had to invite foreigners to impose order among the competing clans since they were incapable of doing so themselves. The Torah then tells us that after the last of these foreign kings died, the Edomites abandoned their attempt to unite, separating into eleven tribal groups.
All this is not surprising; Esau was the very embodiment of haughtiness and arrogance, and his descendants inherited these traits. They could never achieve true unity, since unity requires self-effacement and dedication to the long-term good of the whole, even at the expense of the short-term good of the individual. True self-effacement and dedication to the good of the whole, in turn, is possible only when it stems from our acknowledgment that G-d is the only true reality.
Unity born of true selflessness and dedication to G-d and His vision for our world is the key to peace, harmony, and receiving the fullness of G-d’s blessings.
--Daily Wisdom Volume 3