Adam Clarke on 2 Chronicles 19:4

From Beer-sheba to Mount Ephraim - Before the separation of the ten tribes, in speaking of the extent of the land it was said, From Dan to Beer-sheba; but since that event, the kingdom of Judah was bounded on the south by Beer-sheba, and on the north by the mountains of Ephraim. This shows that Jehoshaphat had gone through all his territories to examine every thing himself, to see that judgment and justice were properly administered among the people.