In the Sinai Desert, G-d says to conduct a census of the twelve tribes of Israel. Moses counts 603,550 men of draftable age (20 to 60 years); the tribe of Levi, numbering 22,300 males age one month and older, is counted separately. The Levites are to serve in the Sanctuary, replacing the firstborn, whose number they approximated, who were disqualified when they participated in the worshipping of the Golden Calf. The 273 firstborn who lacked a Levite to replace them had to pay a five-shekel "ransom" to redeem themselves.

When the people broke camp, the three Levite clans dismantled and transported the Sanctuary, and reassembled it at the center of the next encampment. They then erected their own tents around it: the Kohathites, who carried the Sanctuary's vessels (the Ark, menorah, etc.) in their specially designed coverings on their shoulders, camped to its south; the Gershonites, in charge of its tapestries and roof coverings, to its west; and the families of Merari, who transported its wall panels and pillars, to its north. Before the Sanctuary's entranceway, to its east, were the tents of Moses, Aaron, and Aaron's sons.

Beyond the Levite circle, the twelve tribes camped in four groups of three tribes each. To the east were Judah (pop. 74,600), Issachar (54,400) and Zebulun (57,400); to the south, Reuben (46,500), Simeon (59,300) and Gad (45,650); to the west, Ephraim (40,500), Manasseh (32,200) and Benjamin (35,400); and to the north, Dan (62,700), Asher (41,500) and Naphtali (53,400). This formation was kept also while traveling. Each tribe had its own nassi (prince or leader), and its own flag with its tribal color and emblem.