In the fifth year of King Joram son of Ahab of Israel, Jehoram son of King Jehoshaphat of Judah began to reign.
References for 2 Kings 8:16
He was thirty-two years old when he became king, and he reigned eight years in Jerusalem.
He walked in the way of the kings of Israel, as the house of Ahab had done, for the daughter of Ahab was his wife. He did what was evil in the sight of the Lord.
Yet the Lord would not destroy Judah, for the sake of his servant David, since he had promised to give a lamp to him and to his descendants forever.
In his days Edom revolted against the rule of Judah, and set up a king of their own.
Then Joram crossed over to Zair with all his chariots. He set out by night and attacked the Edomites and their chariot commanders who had surrounded him; but his army fled home.
References for 2 Kings 8:21
So Edom has been in revolt against the rule of Judah to this day. Libnah also revolted at the same time.
Now the rest of the acts of Joram, and all that he did, are they not written in the Book of the Annals of the Kings of Judah?
So Joram slept with his ancestors, and was buried with them in the city of David; his son Ahaziah succeeded him.