Joshua 18:4

Give out from among you If the territory was to be distributed, it was necessary that the more distant portions of the country should be surveyed. Joshua therefore directs the tribes to appoint a commission of twenty-one members, three from each tribe, who should undertake the duty and report to him at Shiloh. Their duty apparently was not so much to carry out an actual measurement of the country, as the preparation of a list of the cities (see Joshua 18:9), and the procuring information respecting the peculiar characteristics of different districts, such as, "what lands were barren and what fertile, whether a district was hilly or flat, whether well-watered or destitute of springs, and anything else which served to shew the goodness of the soil, and the comparative worth of different localities." Rosenmüller.