Edom, which had been subdued by David (2 Samuel 8:14; 1 Kings 11:15–16) but had apparently revolted from Solomon ([Referenc…

The reign of Jehoram, king of Judah. (Compare to 2 Chronicles 21)

In his days Edom revolted from under the hand of Judah
Who had been tributary to Judah ever since the times of David…

A general idea is given of Jehoram's badness. His father, no doubt, had him taught the true knowledge of the Lord, but did wrong to marry him to th…