John Gill 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)

And all the people that were left of the Amorites, Hittites,
Perizzites, Hivites, and Jebusites
Who were not destroyed in the times of Joshua, or since, but dwelt in several cities of the land of Israel from those times; see (Judges 1:1) , which were not of the children of Israel; not natives of the land of Israel, though they might be proselytes, at least some of them.