Numbers 1:48-52

This was because the Lord had told Moses,

“Don't register the tribe of Levi; don't count them in the census with the other Israelites.

Put the Levites in charge of the Tabernacle and of the Testimony, as well as all its furniture and everything it contains. They are the ones responsible for carrying the Tabernacle and all its items. They are to care for it, and to make their camp around it.

When it's time to move the Tabernacle, the Levites shall take it down, and when it's time to make camp, the Levites shall put it up. Any outsider who goes near it must be put to death.

The Israelites are to make camp according to their tribal divisions, each person in their own camp under their own flag.