What does Deuteronomy 3:8 mean?

So at that time, we took the land from the two Amorite kings east of the Jordan, from the Arnon Gorge all the way up to Mount Hermon. Deuteronomy 3:8 - Modern Text Bible

(This verse sums up the territory Israel gained, stretching from the southern border at the Arnon to the northern border at Mount Hermon.)