Joshua 18:9

and passed through the land How long they were absent we are not told. Josephus tells us it was seven months, Ant. v. i. 21. The Rabbis tell us it was seven years. Both suppositions are equally devoid of foundation.

and described it Although the survey was connected chiefly with a general estimate of the resources and characteristics of the several districts, yet it is to be remembered that the Israelites had acquired a knowledge of the art of mensuration in Egypt, where, on account of the annual overflowing of the Nile, it had been practised from the earliest times.

by cities into seven parts i.e. they surveyed it so as to divide the cities and then the land itself into seven parts.