“ Until YHWH has given your brothers rest, as he has given you, and they also have possessed the land which YHWH your God gives them, then you shall return to the land of your possession and possess it, which Moses, the servant of YHWH, gave you in Beyond Jordan, toward the sunrising.”
God's intention was that all his people should have ‘rest' and ‘possess' the land. Possessing it meant working it and making full use of it. Thus His purpose was that they should be able to settle down in peace, security and comfort, sow their fields, care for their flocks and herds, gather their harvests, and worship contentedly. This was now the position of the tribes in Beyond Jordan. They must thus work to ensure that the same became the lot of the whole tribal confederacy.
There was here a great lesson in unselfishness. All the tribes were to look out for each other. How quickly this would be forgotten. Had this unity been maintained, and had all the tribes always responded when called on, the future would have been very different. For that was part of the significance of the covenant, immediate response when one member needed help.
The aim was that as they all gathered three times a year at the appointed feasts at the central sanctuary, to renew their covenant with YHWH and worship Him together, they would recognise that they were one nation with YHWH as their King. And that therefore each part was as important as the next. Unity would be strength. What did later result, as seen in the Book of Judges, was only a poor imitation, and yet without it Israel would not have survived as such.