Asa had become king of the kingdom of Judah several years earlier. He is said to have done a lot that is right in the eyes of the Lord, e.g., in1 Kings 15:11, 1 Kings 15:14. In 2 Chronicles 16:1–6 there is a record of an attack by Baasha in the territory of King Asa of Judah. And that was not the last time it happened. The many battles that these two small countries of Israel and Judah fought with each other meant that their energy was wasted on each other and that they could not play a significant role in the geopolitical relations of that time, as they could in the time of Solomon in particular. God, however, continued to view the two different nations as one people.
32 And there was war between Asa and Baasha king of Israel all their days.