Charles Ellicott Commentary Joshua 22:10

"And when they came unto the region about the Jordan, that is in the land of Canaan, the children of Reuben and the children of Gad and the half-tribe of Manasseh built there an altar by the Jordan, a great altar to look upon." — Joshua 22:10 (ASV)

The borders of Jordan, that are in the land of Canaan. —As far as these words go, the site of the altar might be either east or west of Jordan; but it seems to be more probable that it was on the east bank. And thus the phrase above would be a reminder of the very thing the altar was intended to enforce, namely, the fact that both borders of Jordan are part of the promised land. But Kurn Surtabeth, twenty miles north of Jericho, on the west side of Jordan, has been thought to be the place.