The settlement Reuben and Gad negotiate east of the Jordan in Matot has a dramatic sequel in the book of Joshua: once the two tribes and half of Manasseh return home, they build a large altar on the Jordan's bank, and the tribes west of the river, hearing of it, assemble for war, reading the altar as an act of rebellion against the single sanctuary, before a delegation clarifies that the altar was built only as a witness to shared faith rather than for sacrifice (Joshua 22). The near civil war shows that the settlement Matot records as a negotiated compromise remained, in the biblical narrative's own account, a source of ongoing suspicion between the tribes on either side of the river for at least a generation afterward.
Source critics generally treat the detailed war narrative and spoil-division rules against Midian in this portion as Priestly in style and among the latest-composed material in Numbers, noting its close attention to ritual purification of captured goods and personnel, a concern characteristic of Priestly legislation elsewhere in the Torah, layered onto an older tradition of enmity between Israel and Midian visible already in the Balaam narrative that precedes it. Joshua 22:34 records that the two and a half tribes named the altar itself Ed, 'witness,' explaining in the name the sole, non-sacrificial purpose the delegation had insisted on, so the episode closes with the structure's own name preserving the resolution reached.