Which king reigned for the longest time over the Kingdom of Israel?
More commentary about this passage from The NKJV Study Bible:
“This is the second King of Israel to have this name. Jeroboam I was the founder of the northern kingdom at the time of the death of Solomon (930 B.C., see 1 Kings 11-12). Jeroboam II had a very long reign. His 41 years included ten years as coregent with his father Jehoash.
Jeroboam II did evil in the sight of the Lord. The assessment of his reign is like that of all the kings of Israel, except for the graver assessment given to the house of Ahab.
The Scriptures emphasize Jeroboam’s military prowess. Yet Jeroboam’s might may have also been economic. The well-known Samarian Ostraca, which may date from this period, record the delivery to Samaria of fine oil and barley produced on the royal estates.”