TSK · Numbers 21:20

So Balak brought Balaam to the field of Zophim, to the top of Pisgah, where he built seven altars and offered a bull and a ram on each altar.

These are those who were numbered by Moses and Eleazar the priest, who numbered the Israelites in the rift valley plains of Moab along the Jordan River opposite Jericho.

So it was in the Transjordan, in Moab, that Moses began to deliver these words:

including all the rift valley of the Transjordan in the east to the sea of the rift valley, beneath the slopes of Pisgah.)