Numbers Chapter 2, Order of Encampment and Marching

The Lord said to Moses and Aaron, The sons of Israel shall encamp each by his own standard with the ensigns of their father's houses. They shall encamp facing the tent of meeting on every side. As they encamp, so shall they set out, each in position, standard by standard. These are the sons of Israel as numbered by their fathers houses all in the camps who were numbered by their companies were 603,550. But the Levites were not numbered among the sons ofIsrael as the Lord commanded Moses.