and put Soldiers in Edom, and all Edom became David's servants: for the LORD kept David in all that he took in hand.

These are the kings that reigned in the land of Edom before any king reigned among the children of Israel: Bela the son of Beor, and the name of his city was Dinhabah.

But after the death of Hadad, there were dukes in Edom:

duke Magdiel and duke Iram. These were the dukes of Edom.