The strangers are the non-Israelite population of the holy land, the descendants (chiefly) of those Canaanites whom the children of Israel did not drive out. The reimposition of the bond-service imposed on the Canaanites at the time of the conquest Judges 1:28, Judges 1:30, Judges 1:33, Judges 1:35, but discontinued in the period of depression between Joshua and Saul, was (it is clear) due to David, whom Solomon merely imitated in the arrangements described in these verses.
Related Commentaries of 2 Chronicles 2:17
2 Chronicles 2:17
17 And Solomon numbered all the strangersg that were in the land of Israel, after the numbering wherewith David his father had numbered them; and they were found an hundred and fifty thousand and three thousand and six hundred.