Levites, descendants of Levi or tribe of Levi, were dedicated to service in the Tabernacle and replaced the early priesthood of the first-born among the Israelite people.
The Levitical order continued from the people and were not a privileged class (Exodus 28), nor was the monarchy designed to be so (Deuteronomy 17:14-20), and the people always participated in the coronation of the king and the installation of the high priest. (1 Chronicles 29:22; 1 Maccabees 14:35) They never cultivated the soil nor worked at trades, but were to receive one tenth as tithes from the people; a portion which was divided again to the priests. (Numbers 18:21) Their duty was to instruct the people in the law, which enabled them to spread such knowledge throughout the land. Forty-eight cities were assigned to them, six were cities of refuge, and thirteen were for priests. Each city was to have pasture ground for raising Levite cattle.
This changing of the role of the Levites in relation to the Sanctuary reflects the conflict resulting from the building of the Sanctuary the centralization of it and the reordering of the priesthood after the Exile, through all of which the priesthoods of Aaron and Zadok had to be accommodated.
The tribe of Levi was the only tribe which was not assigned fixed territory in the Promised Land, their religious duties compensated for this and for which they received tithes. The Levites seemed to have been subject to the priests that were descendants of Aaron, but, according to Deuteronomy 18:6-9, all Levites were fit to serve in the Sanctuary.
During this period of the monarchy, Levites became state officials in administration of the government, but eventually became Sanctuary singers. In the aggadah it states the when God purified the twelve tribes, he purified the Levites first. A.G.H.
Smith’s Bible Dictionary, Philadelphia, A. J. Holman, Co., Revised Ed., p. 181-182