“ God forbid that we should rebel against YHWH, and turn away this day from following YHWH, to build an offering for burnt offering, for meal offering, or for sacrifice, besides the altar of YHWH our God which is before his Dwellingplace (Tabernacle).”
The Transjordan tribes then swore through their representatives to be faithful to the command only to offer sacrifices at the Altar of YHWH ‘before His Dwellingplace' (the Tabernacle). (This would not, of course, exclude offering sacrifices on altars exclusively set up at YHWH's command on the basis of Exodus 20:24). Note the threefold repetition of the Name YHWH, putting YHWH at the centre of their thoughts.