Astaroth - On this place compare Genesis 14:5 and note.
In Edrei - These words should, to render the sense clear, come next after “slain.” The battle in which Sihon and Og were defeated took place at Edrei.
Related Commentaries of Deuteronomy 1:4
Deuteronomy 1:4
4 After he had slain Sihon the king of the Amorites, which dwelt in Heshbon, and Og the king of Bashan, which dwelt at Astaroth in Edrei: