Charles Ellicott Commentary 1 Kings 9:20

"As for all the people that were left of the Amorites, the Hittites, the Perizzites, the Hivites, and the Jebusites, who were not of the children of Israel;" — 1 Kings 9:20 (ASV)

A tribute of bond service. This was probably not originated, but simply enforced and organized, by Solomon. It dated, in theory at least, from the Conquest. The most notable example of it is the case of the Gibeonites (Joshua 9:21–27); but there are incidental notices of similar imposition of serfship in Judges 1:28; Judges 1:30; Judges 1:33; Judges 1:35.

Many of the dangers of the stormy age of the Judges were due to the uprising of these subject races, as in the revival of the northern confederacy at Hazor under Sisera (Judges 4:0), and the usurpation of Abimelech by aid of the Shechemites (Judges 9:0). Probably their subordination to Israel varied according to the strength or weakness of each age; but, when the monarchy became organized under David and Solomon, it was fixed definitely and permanently, although, like the serfship of the Middle Ages, it might vary in its severity in different times and in different regions.