The king of Tirzah, one: all the kings thirty and one. King of Tirzah - This city appears to have been for a long time the capital of the kingdom of Israel, and the residence of its kings. See 1 Kings 14:17; 1 Kings 15:21, 1 Kings 15:33. Its situation cannot be exactly ascertained; but it is supposed to have been situated on a mountain about three leagues south of Samaria.
All the kings thirty and one - The Septuagint say εικοσι εννεα, twenty-nine, and yet set down but twenty-eight, as they confound or omit the kings of Beth-el, Lasharon, and Madon.
So many kings in so small a territory, shows that their kingdoms must have been very small indeed. The kings of Beth-el and Ai had but about 12,000 subjects in the whole; but in ancient times all kings had very small territories. Every village or town had its chief; and this chief was independent of his neighbors, and exercised regal power in his own district. In reading all ancient histories, as well as the Bible, this circumstance must be kept constantly in view; for we ought to consider that in those times both kings and kingdoms were but a faint resemblance of those now.
Great Britain, in ancient times, was divided into many kingdoms: in the time of the Saxons it was divided into seven, hence called the Saxon heptarchy. But when Julius Caesar first entered this island, he found four kings in Kent alone; Cingetorix, Carnilius, Taximagulus, and Segonax. Hence we need not wonder at the numbers we read of in the land of Canaan. Ancient Gaul was thus divided; and the great number of sovereign princes, secular bishops, landgraves, dukes, etc., etc., in Germany, are the modern remains of those ancient divisions.
Commentary on the Bible, by Adam Clarke [1831].