The book of Numbers resumes the history of Israel's sojourn in the wilderness.   Egypt lay in the past, the Promised Land was still ahead of them in the future, but Israel's destiny depended on their present obedience.  This is a book of conflict -- against external enemies, against internal factions, and with God Himself.  It is in Numbers that Israel's failure to obey God resulted in the interruption of His plan, and the prolonging of their wanderings for 40 years.  This book also contains some very significant racial teaching.   
       
Israel could not stay camped at Mt Sinai, although perhaps it would have been a good idea to remain there longer:  the community needed to organize and stabilize, and adjust to the new laws.  Much attention was given to the proper  marching order of the tribes (Num 2).  The Israelites did not travel in an unruly mass.  The God who was concerned about skin conditions in Leviticus also had a plan for the distribution of the people.  First He had Moses and Aaron count them (Num 1), then arranged them by tribes in a square, three tribes per side (Num 2).  The Levites and the tent of meeting were in the center of the square.  This must have been a massive encampment.  The total population was over 600,000 men, not including Levites (Num 2:32-3).

         

An alternative layout of the encampment, from a Christian author, is that it had the form of a gigantic cross (see Cornwall, Let Us Draw Near).