After recounting the victory over Sihon, Moses turns to describe the next military success, namely, the one over Og the king of Bashan. Bashan was the northernmost region of the Transjordan region, and therefore Israel's conquest of Bashan too them of their route and to the north of the point where they would cross the Jordan. The battle took place at Edrei, one of the royal residences of Og (Deuteronomy 1:4).
1 “Then we turned and went up the way to Bashan. And Og the king of Bashan came out against us, he and all his people, to battle at Edrei.