Albert Barnes Commentary 1 Chronicles 9:2

"Now the first inhabitants that dwelt in their possessions in their cities were Israel, the priests, the Levites, and the Nethinim." — 1 Chronicles 9:2 (ASV)

The first inhabitants—that is, the first inhabitants of the holy land after the return from the captivity. They are enumerated under four heads:

1. Israelites, meaning the mass of the laity, whether belonging to the ten tribes or the two.
2. Priests.
3. Levites.
4. The lowest order of the ministry, the Nethinims.

These last, whose name is derived from a root meaning “to give,” were a kind of sacred servant—persons “given” to the Levites to perform the more laborious duties of the sanctuary. Some had been “given” as early as the time of Moses (Numbers 31:47), and the number afterward increased (Joshua 9:23; Ezra 8:20).

At the time of the return from the captivity, the services of the Nethinims became very important, owing to the small number of Levites who came back (Ezra 2:40–42). They are mentioned by the name Nethinims only in Chronicles, Ezra, and Nehemiah.