Jehoram's disobedience led to the loss of what Asa and Jehoshaphat had achieved.
Edom has been in rebellion: During Solomon's reign, controlling Edom allowed Israel to access rich Arabian trade. The Edomites had also rebelled before Solomon's death (1 Kings 11:14–22) and were likely not under Rehoboam's control. They seemed to come under Judah's control again after Jehoshaphat defeated them (2 Chronicles 20:1–30; compare 1 Kings 22:47).
The town of Libnah was at the western end of the Valley of Elah, on the border of Philistine territory.