The Israelites were commanded by God to conduct a census of all the tribes, counting men from 20 years and older, to determine each tribe's numerical strength for future combat. The Levites were exempted from this census, but Moses counted them separately later. The camp was arranged by tribes, with the order in which they were to set out and regroup later also specified. The sons of Aaron were ordained as the chief priests, and the Levites as their assistants, with each of the three sons of Levi (Kohath, Merari, and Gershom) in charge of different aspects of the tabernacle when it was to be disassembled, transported, and reassembled in the next location.
